EXHIBIT 4.1


                                                               EXECUTION VERSION

                      AMENDED AND RESTATED TRUST AGREEMENT

                          dated as of February 26, 2004

                                      among

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.,
                   as Depositor and Certificate Administrator,

                                 CITIBANK, N.A.,
                                   as Trustee

                                       and

                        CHRISTIANA BANK & TRUST COMPANY,
                               as Delaware Trustee




                   Washington Mutual Mortgage Securities Corp.

                     WaMu Mortgage Pass-Through Certificates
                                 Series 2004-RS1

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                                TABLE OF CONTENTS
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                                                                                                               Page
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ARTICLE I........................................................................................................5

         Section 1.01.         Definitions.......................................................................5
                  Administrative Officer.........................................................................5
                  Aggregate Certificate Principal Balance........................................................5
                  Allocated Realized Loss........................................................................5
                  Allocated Uncompensated Interest Shortfall.....................................................6
                  Authenticating Agent...........................................................................6
                  Authorized Denomination........................................................................6
                  Avoided Payment................................................................................6
                  Bankruptcy Coverage............................................................................6
                  Bankruptcy Loss................................................................................6
                  Beneficial Holder..............................................................................7
                  Benefit Plan Opinion...........................................................................7
                  Book-Entry Certificates........................................................................7
                  Business Day...................................................................................7
                  Certificate....................................................................................7
                  Certificate Account............................................................................7
                  Certificate Administrator......................................................................7
                  Certificate Administrator Fee..................................................................7
                  Certificateholder or Holder....................................................................7
                  Certificate Insurance Policy...................................................................8
                  Certificate Insurer............................................................................8
                  Certificate Insurer Default....................................................................8
                  Certificate Insurer Premium....................................................................8
                  Certificate Interest Rate......................................................................9
                  Certificate of Trust...........................................................................9
                  Certificate Principal Balance..................................................................9
                  Certificate Register and Certificate Registrar.................................................9
                  Class..........................................................................................9
                  Class A Certificates...........................................................................9
                  Class A-L Regular Interests....................................................................9
                  Class A-1 Certificates.........................................................................9
                  Class A-1-L Regular Interest...................................................................9
                  Class A-2 Certificates........................................................................10
                  Class A-2-L Regular Interest..................................................................10
                  Class A-3 Certificates........................................................................10
                  Class A-3 Covered Shortfall Amount............................................................10
                  Class A-3 Priority Amount.....................................................................10
                  Class A-3 Reimbursement Amount................................................................10
                  Class A-3 Reserve Fund........................................................................10
                  Class A-3-L Regular Interest..................................................................10
                  Class A-4 Certificates........................................................................10
                  Class A-4-L Regular Interest..................................................................10
                  Class A-5 Certificates........................................................................10
                  Class A-5-L Regular Interest..................................................................10
                  Class A-6 Certificates........................................................................10

                                                                       i

<PAGE>

                  Class A-6 Priority Amount.....................................................................11
                  Class A-6-L Regular Interest..................................................................11
                  Class A-7 Certificates........................................................................11
                  Class A-7-L Regular Interest..................................................................11
                  Class A-8 Certificates........................................................................11
                  Class A-8-L Regular Interest..................................................................11
                  Class A-9 Certificates........................................................................11
                  Class A-9 Notional Amount.....................................................................11
                  Class A-10 Certificates.......................................................................11
                  Class A-10-L Regular Interest.................................................................11
                  Class A-11 Certificates.......................................................................11
                  Class A-11-L Regular Interest.................................................................11
                  Class A-12 Certificates.......................................................................11
                  Class A-12-L Regular Interest.................................................................11
                  Class A-13 Certificates.......................................................................11
                  Class A-13-L Regular Interest.................................................................11
                  Class A-14 Certificates.......................................................................12
                  Class A-14 Notional Amount....................................................................12
                  Class A-15 Certificates.......................................................................12
                  Class A-15-L Regular Interest.................................................................12
                  Class A-16 Certificates.......................................................................12
                  Class A-16 Notional Amount....................................................................12
                  Class A-17 Certificates.......................................................................12
                  Class A-17-L Regular Interest.................................................................12
                  Class A-18 Certificates.......................................................................12
                  Class A-18 Notional Amount....................................................................12
                  Class A-19 Accretion Termination Date.........................................................12
                  Class A-19 Accrual Amount.....................................................................12
                  Class A-19 Certificates.......................................................................12
                  Class A-19-L Regular Interest.................................................................12
                  Class A-20 Accretion Termination Date.........................................................13
                  Class A-20 Accrual Amount.....................................................................13
                  Class A-20 Certificates.......................................................................13
                  Class A-20-L Regular Interest.................................................................13
                  Class B Certificates..........................................................................13
                  Class Notional Amount.........................................................................13
                  Class Principal Balance.......................................................................13
                  Class R Certificates..........................................................................14
                  Class R Residual Interests....................................................................14
                  Class R-1 Residual Interest...................................................................14
                  Class R-2 Residual Interest...................................................................14
                  Clean-Up Call Percentage......................................................................14
                  Clearing Agency...............................................................................14
                  Closing Date..................................................................................15
                  Code..........................................................................................15

                                                                       ii

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                  Company.......................................................................................15
                  Corporate Trust Office........................................................................15
                  Corporation...................................................................................15
                  Corresponding Class...........................................................................15
                  Credit Support Depletion Date.................................................................15
                  Cut-Off Date..................................................................................15
                  Deceased Holder...............................................................................15
                  Deficiency Amount.............................................................................16
                  Definitive Certificates.......................................................................16
                  Delaware Trustee..............................................................................16
                  Depositary Agreement..........................................................................16
                  Determination Date............................................................................16
                  Disqualified Organization.....................................................................16
                  Distribution Date.............................................................................16
                  DTC...........................................................................................16
                  DTC Participant...............................................................................16
                  Eligible Institution..........................................................................16
                  ERISA.........................................................................................16
                  Event of Default..............................................................................16
                  FDIC..........................................................................................16
                  Final Maturity Date...........................................................................16
                  Fitch.........................................................................................16
                  Fraud Coverage................................................................................16
                  Fraud Loss....................................................................................17
                  Freddie Mac...................................................................................17
                  Indirect DTC Participants.....................................................................17
                  Insurance Agreement...........................................................................17
                  Insured Certificates..........................................................................17
                  Insured Payment...............................................................................17
                  Interest Distribution Amount..................................................................17
                  Investment Depository.........................................................................17
                  Last Scheduled Distribution Date..............................................................17
                  Late Payment Rate.............................................................................17
                  LIBOR.........................................................................................17
                  LIBOR Determination Date......................................................................18
                  Living Holder.................................................................................18
                  Lockout Percentage............................................................................19
                  Lockout Priority Amount.......................................................................19
                  Master Servicer...............................................................................19
                  Mortgage Loan Schedule........................................................................19
                  Mortgage Loans................................................................................19
                  Nonpayment....................................................................................19
                  Non-U.S. Person...............................................................................19
                  Notice........................................................................................19
                  Notice Addresses..............................................................................19


                                                                       iii
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                  OTS...........................................................................................20
                  Officer's Certificate.........................................................................20
                  Opinion of Counsel............................................................................20
                  Original Trust Agreement......................................................................20
                  Owner.........................................................................................20
                  Ownership Interest............................................................................20
                  Pass-Through Entity...........................................................................20
                  Paying Agent..................................................................................20
                  Percentage Interest...........................................................................20
                  Permitted Transferee..........................................................................21
                  Person........................................................................................21
                  Planned Principal Balance.....................................................................21
                  Pooling and Servicing Agreement...............................................................21
                  Principal Balance.............................................................................22
                  Principal Distribution Amount.................................................................22
                  Prior Period..................................................................................22
                  Pro Rata Allocation...........................................................................22
                  Prospectus....................................................................................22
                  Random Lot....................................................................................22
                  Rating Agency.................................................................................22
                  Ratings.......................................................................................22
                  Record Date...................................................................................22
                  Reference Banks...............................................................................22
                  Regular Interests.............................................................................22
                  REMIC.........................................................................................22
                  REMIC Provisions..............................................................................23
                  REMIC I.......................................................................................23
                  REMIC I Assets................................................................................23
                  REMIC I Available Distribution Amount.........................................................23
                  REMIC I Distribution Amount...................................................................23
                  REMIC I Regular Interests.....................................................................28
                  REMIC II......................................................................................28
                  REMIC II Assets...............................................................................28
                  REMIC II Available Distribution Amount........................................................28
                  REMIC II Distribution Amount..................................................................28
                  REMIC II Regular Interests....................................................................29
                  Residual Certificates.........................................................................29
                  Residual Distribution Amount..................................................................29
                  Responsible Officer...........................................................................29
                  Rounding Account..............................................................................30
                  Rounding Amount...............................................................................30
                  S&P...........................................................................................30
                  Scheduled Payment.............................................................................30
                  Secretary of State............................................................................30
                  Securities Act................................................................................30


                                                                      iv
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                  Special Retail Certificates...................................................................30
                  Statutory Trust Statute.......................................................................31
                  Step Down Percentage..........................................................................31
                  Tax Matters Person............................................................................31
                  Termination Date..............................................................................31
                  Termination Payment...........................................................................31
                  Transfer......................................................................................31
                  Transferee....................................................................................31
                  Transferee Affidavit and Agreement............................................................32
                  Trust.........................................................................................32
                  Trust Assets..................................................................................32
                  Trustee.......................................................................................32
                  Underlying Certificates.......................................................................32
                  Underlying Trust..............................................................................32
                  Underwriter...................................................................................32
                  U.S. Person...................................................................................32


ARTICLE II            Creation of the Trust; Conveyance of the Trust Assets and REMIC I Regular Interests; REMIC Election
                      and Designations; Original Issuance of Certificates.......................................32

         Section 2.01.         Creation of the Trust............................................................32
         Section 2.02.         Restrictions on Activities of the Trust..........................................33
         Section 2.03.         Separateness Requirements........................................................34
         Section 2.04.         Conveyance of Trust Assets; Security Interest....................................35
         Section 2.05.         [Reserved].......................................................................37
         Section 2.06.         REMIC Election for REMIC I.......................................................37
         Section 2.07.         [Reserved].......................................................................38
         Section 2.08.         Representations and Warranties of the Company....................................38
         Section 2.09.         Acknowledgment of Transfer of Trust Assets.......................................38
         Section 2.10.         Conveyance of REMIC I Regular Interests; Security Interest.......................38
         Section 2.11.         REMIC Election for REMIC II......................................................40
         Section 2.12.         Acknowledgement of Transfer of REMIC II Assets; Authentication of Certificates...41
         Section 2.13.         Legal Title......................................................................41
         Section 2.14.         Compliance with ERISA Requirements...............................................41

ARTICLE III           Administration of the Underlying Certificates.............................................41

         Section 3.01.         The Company to Act as Certificate Administrator..................................41
         Section 3.02.         [Reserved].......................................................................42
         Section 3.03.         [Reserved].......................................................................42
         Section 3.04.         The Certificate Account..........................................................42
         Section 3.05.         [Reserved].......................................................................42
         Section 3.06.         [Reserved].......................................................................42
         Section 3.07.         [Reserved].......................................................................42
         Section 3.08.         [Reserved].......................................................................42


                                                                       v
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         Section 3.09.         Compliance with Federal Withholding Requirements.................................42
         Section 3.10.         [Reserved].......................................................................42
         Section 3.11.         Compensation to the Certificate Administrator....................................42
         Section 3.12.         Reports to the Trustee; Certificate Account Statement............................43
         Section 3.13.         Annual Statement as to Compliance................................................43
         Section 3.14.         [Reserved].......................................................................43
         Section 3.15.         Annual Independent Public Accountants' Servicing Report..........................43
         Section 3.16.         Maintenance of the Class A-3 Reserve Fund........................................43
         Section 3.17.         [Reserved.]......................................................................44
         Section 3.18.         [Reserved.]......................................................................44
         Section 3.19.         [Reserved.]......................................................................44
         Section 3.20.         [Reserved.]......................................................................44
         Section 3.21.         Maintenance of the Certificate Insurance Policy; Collections Thereunder..........44
         Section 3.22.         Maintenance of the Rounding Account; Collections Thereunder......................45

ARTICLE IV            Payments to Certificateholders; Payment of Expenses.......................................46

         Section 4.01.         Distributions to Certificate Insurer and Holders of REMIC I Regular Interests and Class R-1
                               Residual Interest................................................................46
         Section 4.02.         Distribution Reports to the Trustee..............................................47
         Section 4.03.         [Reserved.]......................................................................47
         Section 4.04.         Distributions to Certificateholders; Payment of Certificate Administrator Fee....47
         Section 4.05.         Statements to Certificateholders.................................................49
         Section 4.06.         Principal Distributions on the Special Retail Certificates.......................49

ARTICLE V             The Certificates..........................................................................53

         Section 5.01.         The Certificates.................................................................53
         Section 5.02.         Certificates Issuable in Classes; Distributions of Principal and Interest; Authorized
                               Denominations....................................................................57
         Section 5.03.         Registration of Transfer and Exchange of Certificates............................58
         Section 5.04.         Mutilated, Destroyed, Lost or Stolen Certificates................................58
         Section 5.05.         Persons Deemed Owners............................................................59
         Section 5.06.         Temporary Certificates...........................................................59
         Section 5.07.         Book-Entry for Book-Entry Certificates...........................................59
         Section 5.08.         Notices to Clearing Agency.......................................................60
         Section 5.09.         Definitive Certificates..........................................................61
         Section 5.10.         Office for Transfer of Certificates..............................................61
         Section 5.11.         Nature of Certificates...........................................................61

ARTICLE VI            The Company and the Certificate Administrator.............................................62

         Section 6.01.         Liability of the Company and the Certificate Administrator.......................62
         Section 6.02.         Merger or Consolidation of the Company, or the Certificate Administrator.........62




                                                                     vi
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         Section 6.03.         Limitation on Liability of the Company, the Certificate Administrator and Others.62
         Section 6.04.         The Company and the Certificate Administrator not to Resign......................63
         Section 6.05.         Trustee Access...................................................................63

ARTICLE VII           Default...................................................................................63

         Section 7.01.         Events of Default................................................................63
         Section 7.02.         Trustee to Act; Appointment of Successor.........................................65
         Section 7.03.         Notification to Certificateholders...............................................66

ARTICLE VIII          Concerning the Trustees...................................................................66

         Section 8.01.         Duties of Trustees...............................................................66
         Section 8.02.         Certain Matters Affecting the Trustees...........................................68
         Section 8.03.         Trustees Not Liable for Certificates or Underlying Certificates..................69
         Section 8.04.         Trustees May Own Certificates....................................................69
         Section 8.05.         The Certificate Administrator to Pay Trustees' Fees and Expenses.................69
         Section 8.06.         Eligibility Requirements for Trustees............................................70
         Section 8.07.         Resignation and Removal of Trustees..............................................70
         Section 8.08.         Successor Trustee................................................................71
         Section 8.09.         Merger or Consolidation of Trustee...............................................72
         Section 8.10.         Appointment of Co-Trustee or Separate Trustee....................................72
         Section 8.11.         Authenticating Agents............................................................73
         Section 8.12.         Paying Agents....................................................................74
         Section 8.13.         Duties of Delaware Trustee.......................................................75
         Section 8.14.         Amendment to Certificate of Trust................................................75
         Section 8.15.         Limitation of Liability..........................................................75

ARTICLE IX            Termination...............................................................................75

         Section 9.01.         Termination Upon Purchase by the Certificate Administrator of the Underlying Certificates   75
         Section 9.02.         Additional Termination Requirements..............................................77
         Section 9.03.         Trust Irrevocable................................................................78

ARTICLE X             Miscellaneous Provisions..................................................................78

         Section 10.01.        Amendment........................................................................78
         Section 10.02.        [Reserved.]......................................................................79
         Section 10.03.        Limitation on Rights of Certificateholders.......................................79
         Section 10.04.        Access to List of Certificateholders.............................................80
         Section 10.05.        Governing Law....................................................................81
         Section 10.06.        Notices..........................................................................81
         Section 10.07.        Severability of Provisions.......................................................81
         Section 10.08.        Counterpart Signatures...........................................................81
         Section 10.09.        Benefits of Agreement............................................................81
         Section 10.10.        Notices and Copies to Rating Agencies............................................82


                                                                   vii

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Exhibit A      Form of Certificates (other than Class R Certificates)
Exhibit B      Form of Class R Certificates
Exhibit C      [Reserved]
Exhibit E      Selling And Servicing Contract
Exhibit F      [Reserved]
Exhibit G      [Reserved]
Exhibit H      Form of Additional Matter Incorporated Into The Certificates
Exhibit I      Transferor Certificate
Exhibit J      Transferee Affidavit And Agreement
Exhibit K      Form of Certificate Insurance Policy

</TABLE>


                                        viii

<PAGE>



         This Amended and Restated Trust Agreement, dated and effective as of
February 26, 2004 (this "Agreement"), is executed by and among Washington Mutual
Mortgage Securities Corp., as depositor and Certificate Administrator (the
"Company"), Citibank, N.A., a national banking association with a corporate
trust office at 111 Wall Street, 14th Floor, Zone 3, New York, New York 10005,
as Trustee (the "Trustee"), and Christiana Bank & Trust Company, as Delaware
Trustee (the "Delaware Trustee"). Capitalized terms used in this Agreement and
not otherwise defined have the meanings ascribed to such terms in Article I
hereof.

                              PRELIMINARY STATEMENT

         The Company at the Closing Date is the owner of the Underlying
Certificates and the other property being conveyed by it to the Trust. On the
Closing Date, the Company will acquire the REMIC I Regular Interests and the
Class R-1 Residual Interest from the Trust as consideration for its transfer to
the Trust of the Underlying Certificates and certain other assets and will be
the owner of the REMIC I Regular Interests and the Class R-1 Residual Interest.
Thereafter on the Closing Date, the Company will acquire the Certificates (other
than the Class R Certificates) and the Class R-2 Residual Interest from the
Trust as consideration for its transfer to the Trust of the REMIC I Regular
Interests and will be the owner of the Certificates. The Company has duly
authorized the execution and delivery of this Agreement to provide for (i) the
conveyance to the Trust of the Underlying Certificates and certain other assets,
(ii) the issuance to the Company of the REMIC I Regular Interests and the Class
R-1 Residual Interest representing in the aggregate the entire beneficial
interest in REMIC I, (iii) the conveyance to the Trust of the REMIC I Regular
Interests and (iv) the issuance to the Company of the Certificates, such
Certificates (other than the portion of the Class R Certificates representing
ownership of the Class R-1 Residual Interest) representing in the aggregate the
entire beneficial interest in REMIC II. The Company is entering into this
Agreement, and the Trustee and the Delaware Trustee are each accepting the trust
created hereby, for good and valuable consideration, the receipt and sufficiency
of which are hereby acknowledged.

         The Certificates issued hereunder have been offered for sale pursuant
to a Prospectus, dated February 10, 2004, and a Prospectus Supplement, dated
February 24, 2004, of the Company (together, the "Prospectus"). The Trust
created hereunder is intended to be the "Trust" described in the Prospectus and
the Certificates are intended to be the "Certificates" described therein. The
following tables set forth the designation, type of interest, Certificate
Interest Rate, initial Class Principal Balance and Final Maturity Date for the
REMIC I Regular Interests, the Class R Residual Interests and the Certificates:






                                       1
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<TABLE>
<CAPTION>
                                                               REMIC I Interests

    Class Designation for
    each REMIC I Regular
   Interest and the Class                         Certificate            Initial Class
    R-1 Residual Interest       Type of            Interest                Principal
                               Interest            Rate (1)                 Balance             Final Maturity Date*
  ------------------------    ------------    --------------------    --------------------     ------------------------
  <S>                         <C>             <C>                     <C>                      <C>
  Class A-1-L                  Regular             4.500%                $107,707,858.00          November 2033
  Class A-2-L                  Regular             5.500%                  13,963,546.00          November 2033
  Class A-3-L                  Regular             5.500%                  15,000,000.00          November 2033
  Class A-4-L                  Regular             5.500%                  36,750,000.00          November 2033
  Class A-5-L                  Regular             5.500%                   4,587,000.00          November 2033
  Class A-6-L                  Regular             (2)                        245,454.00          November 2033
  Class A-7-L                  Regular             4.500%                  62,402,144.00          November 2033
  Class A-8-L                  Regular             8.000%                  39,960,856.00          November 2033
  Class A-10-L                 Regular             5.500%                   9,070,472.00          November 2033
  Class A-11-L                 Regular             5.500%                  30,597,000.00          November 2033
  Class A-12-L                 Regular             (2)                      1,130,449.00          November 2033
  Class A-13-L                 Regular             8.000%                  43,083,142.00          November 2033
  Class A-15-L                 Regular             4.750%                  23,779,000.00          November 2033
  Class A-17-L                 Regular             4.750%                  25,396,000.00          November 2033
  Class A-19-L                 Regular             4.750%(3)                   25,000.00          November 2033
  Class A-20-L                 Regular             4.750%(4)                  800,000.00          November 2033
  Class R-1 +                  Residual            5.485%                         100.00          November 2033
</TABLE>

*    The Distribution Date in the specified month, which is the month following
     the month the latest maturing Mortgage Loan matures. For federal income tax
     purposes, for each Class of REMIC I Regular and Residual Interests, the
     "latest possible maturity date" shall be the Final Maturity Date.

+    The Class R-1 Residual Interest is entitled to receive the applicable
     Residual Distribution Amount.

(1)  Interest distributed to the REMIC I Regular Interests (other than the Class
     A-6-L and Class A-12-L Regular Interests, which shall not be entitled to
     receive any distributions of interest) and the Class R-1 Residual Interest
     on each Distribution Date will have accrued at the applicable per annum
     Certificate Interest Rate on the applicable Class Principal Balance
     outstanding immediately before such Distribution Date.

(2)  The Class A-6-L and Class A-12-L Regular Interests shall not be entitled to
     receive any distributions of interest.

(3)  On each Distribution Date on or before the Class A-19 Accretion Termination
     Date, an amount equal to the Class A-19 Accrual Amount shall be added to
     the Class A-19-L Principal Balance, and such amount shall be distributed as
     principal to certain Classes of Class A-L Regular Interests and shall not
     be distributed as interest to the Class A-19-L Regular Interest.

(4)  On each Distribution Date on or before the Class A-20 Accretion Termination
     Date, an amount equal to the Class A-20 Accrual Amount shall be added to
     the Class A-20-L Principal Balance, and such amount shall be distributed as
     principal to certain Classes of Class A-L Regular Interests and shall not
     be distributed as interest to the Class A-20-L Regular Interest.


         As provided herein, with respect to REMIC I, the Company will cause an
election to be made on behalf of REMIC I to be treated for federal income tax
purposes as a REMIC. The REMIC I Regular Interests will be designated regular
interests in REMIC I and the Class R-1 Residual Interest will be designated the
sole class of residual interest in REMIC I, for purposes of the REMIC
Provisions.



                                       2
<PAGE>




<TABLE>
<CAPTION>
                                                               REMIC II Interests

    Class Designation for
        each Class of
        Certificates                              Certificate            Initial Class
      and the Class R-2         Type of            Interest                Principal               Final Maturity
      Residual Interest        Interest            Rate (1)                 Balance                     Date*
  ------------------------    ------------    --------------------    --------------------     ------------------------
  <S>                         <C>             <C>                     <C>                      <C>
  Class A-1                    Regular             4.500%                $107,707,858.00          November 2033
  Class A-2                    Regular             5.500%                  13,963,546.00          November 2033
  Class A-3                    Regular             5.500%                  15,000,000.00          November 2033
  Class A-4                    Regular             5.500%                  36,750,000.00          November 2033
  Class A-5                    Regular             5.500%                   4,587,000.00          November 2033
  Class A-6                    Regular             (2)                        245,454.00          November 2033
  Class A-7                    Regular             4.500%                  62,402,144.00          November 2033
  Class A-8                    Regular             (3)                     39,960,856.00          November 2033
  Class A-9                    Regular             (4)                          -----             November 2033
  Class A-10                   Regular             5.500%                   9,070,472.00          November 2033
  Class A-11                   Regular             5.500%                  30,597,000.00          November 2033
  Class A-12                   Regular             (2)                      1,130,449.00          November 2033
  Class A-13                   Regular             (5)                     43,083,142.00          November 2033
  Class A-14                   Regular             (6)                          -----             November 2033
  Class A-15                   Regular             4.000%                  23,779,000.00          November 2033
  Class A-16                   Regular             5.500%(7)                    -----             November 2033
  Class A-17                   Regular             4.700%                  25,396,000.00          November 2033
  Class A-18                   Regular             5.500%(7)                    -----             November 2033
  Class A-19                   Regular             4.750%(8)                   25,000.00          November 2033
  Class A-20                   Regular             4.750%(9)                  800,000.00          November 2033
  Class R-2 (10)               Residual              -----                      -----             November 2033
</TABLE>

*    The Distribution Date in the specified month, which is the month following
     the month the latest maturing Mortgage Loan matures. For federal income tax
     purposes, for each Class of REMIC II Regular and Residual Interests, the
     "latest possible maturity date" shall be the Final Maturity Date.

(1)  Interest distributed on each Distribution Date to the Certificates (other
     than the Class A-6 and Class A-12 Certificates, which shall not be entitled
     to receive any distributions of interest) will have accrued at the
     applicable per annum Certificate Interest Rate on the applicable Class
     Principal Balance or Class Notional Amount outstanding immediately before
     such Distribution Date.

(2)  The Class A-6 and Class A-12 Certificates shall not be entitled to receive
     any distributions of interest.

(3)  The Certificate Interest Rate for the Class A-8 Certificates shall equal
     LIBOR plus 0.450%, subject to a minimum and maximum Certificate Interest
     Rate of 0.450% and 8.000% per annum, respectively.

(4)  The Certificate Interest Rate for the Class A-9 Certificates shall equal
     7.550% minus LIBOR, subject to a minimum and maximum Certificate Interest
     Rate of 0.000% and 7.550% per annum, respectively. The Class A-9
     Certificates shall accrue interest on the Class A-9 Notional Amount. The
     Class A-9 Certificates shall not be entitled to receive any distributions
     of principal.

(5)  The Certificate Interest Rate for the Class A-13 Certificates shall equal
     LIBOR plus 0.500%, subject to a minimum and maximum Certificate Interest
     Rate of 0.500% and 8.000% per annum, respectively.

(6)  The Certificate Interest Rate for the Class A-14 Certificates shall equal
     7.500% minus LIBOR, subject to a minimum and maximum Certificate Interest
     Rate of 0.000% and 7.500% per annum, respectively. The Class A-14
     Certificates shall accrue interest on the Class A-14 Notional Amount. The
     Class A-14 Certificates shall not be entitled to receive any distributions
     of principal.

(7)  Each Class of the Class A-16 and Class A-18 Certificates shall accrue
     interest on the related Class Notional Amount. The Class A-16 and Class
     A-18 Certificates shall not be entitled to receive any distributions of
     principal.

(8)  On each Distribution Date on or before the Class A-19 Accretion Termination
     Date, an amount equal to the Class A-19 Accrual Amount shall be added to
     the Class A-19 Principal Balance, and such amount shall be distributed as
     principal to certain Classes of Class A Certificates and shall not be
     distributed as interest to the Class A-19 Certificates.

                                       3
<PAGE>

(9)  On each Distribution Date on or before the Class A-20 Accretion Termination
     Date, an amount equal to the Class A-20 Accrual Amount shall be added to
     the Class A-20 Principal Balance, and such amount shall be distributed as
     principal to certain Classes of Class A Certificates and shall not be
     distributed as interest to the Class A-20 Certificates.

(10) The Class R-2 Residual Interest shall be entitled to receive the applicable
     Residual Distribution Amount. The Class R-2 Residual Interest shall not be
     entitled to receive any distributions of interest or principal.

         As provided herein, with respect to REMIC II, the Company will cause an
election to be made on behalf of REMIC II to be treated for federal income tax
purposes as a REMIC. The Certificates (other than the Class R Certificates) will
be designated regular interests in REMIC II, and the Class R-2 Residual Interest
will be designated the sole class of residual interest in REMIC II, for purposes
of the REMIC Provisions. As of the Closing Date, the Underlying Certificates
have a Class Principal Balance of $414,498,021. As of the Closing Date, the
Certificates have an Aggregate Certificate Principal Balance of $414,498,021.

         In addition, the Trust will issue the Class R Certificates, which will
represent ownership of the Class R-1 and Class R-2 Residual Interests.


                              W I T N E S S E T H :

         WHEREAS, the Company is a corporation duly organized and existing under
and by virtue of the laws of the State of Delaware and has full corporate power
and authority to enter into this Agreement and to undertake the obligations
undertaken by it herein;

         WHEREAS, the Trustee is a national banking association duly organized
and existing under the laws of the United States of America and has full power
and authority to enter into this Agreement;

         WHEREAS, the Delaware Trustee is a banking corporation duly organized
and existing under the laws of the State of Delaware and has full power and
authority to enter into this Agreement;

         WHEREAS, prior to the execution and delivery hereof, the Company and
the Delaware Trustee have entered into the Original Trust Agreement, and the
Delaware Trustee has filed the Certificate of Trust;

         WHEREAS, it is the intention of the Company, the Trustee and the
Delaware Trustee that the Trust created by this Agreement constitute a statutory
trust under the Statutory Trust Statute, that this Agreement constitute the
governing instrument of the Trust, and that this Agreement amend and restate the
Original Trust Agreement;

         WHEREAS, the Company is the owner of the Underlying Certificates on the
Closing Date; and

                                       4
<PAGE>

         WHEREAS, the Company has been duly authorized to create the Trust to
(i) hold the Underlying Certificates and certain other property, (ii) issue the
REMIC I Regular Interests and the Class R-1 Residual Interest, (iii) hold the
REMIC I Regular Interests and (iv) issue the Certificates.

         NOW, THEREFORE, in order to declare the terms and conditions upon which
the REMIC I Regular Interests, the Class R Residual Interests and the
Certificates are to be issued, and in consideration of the premises and of the
purchase and acceptance of the Certificates by the Holders thereof, the Company
covenants and agrees with the Trustee and the Delaware Trustee, for the equal
and proportionate benefit of the respective Holders from time to time of the
REMIC I Regular Interests and the Certificates, as applicable, as follows:

                                   ARTICLE I



Section 1.01.     Definitions.

         Whenever used in this Agreement, the following words and phrases,
unless the context otherwise requires, shall have the following meanings:

         Administrative Officer: Any officer of the Certificate Administrator
involved in, or responsible for, the administration of the Certificates, whose
name and specimen signature appear on a list of servicing officers furnished to
the Trustee by the Certificate Administrator, as such list may from time to time
be amended.

         Aggregate Certificate Principal Balance: At any given time, the sum of
the then current Class Principal Balances of the Certificates.

         Allocated Realized Loss: For any Distribution Date, any Realized Loss
(as defined in the Pooling and Servicing Agreement) allocated to the Underlying
Certificates pursuant to the definition of "Realized Loss" in the Pooling and
Servicing Agreement.

         Allocated Realized Losses shall be allocated among the REMIC I Regular
Interests (i) for Allocated Realized Losses allocable to principal, to the Class
A-L Regular Interests, pro rata according to the Class Principal Balance
thereof, in reduction thereof; and (ii) for Allocated Realized Losses allocable
to interest, to the Class A-L Regular Interests (other than the Class A-6-L and
Class A-12-L Regular Interests), pro rata according to accrued but unpaid
interest on such Classes, in reduction thereof, and then to the Class A-L
Regular Interests (other than the Class A-6-L and Class A-12-L Regular
Interests), pro rata according to the Class Principal Balances thereof, in
reduction thereof; provided, however, that until the Class A-5 Principal Balance
has been reduced to zero, all principal losses (other than Allocated Realized
Losses allocated to the Underlying Certificates by Pro Rata Allocation) that
would otherwise be allocated to the Class A-4 and Class A-7 Certificates
pursuant to clause (i) of this paragraph shall instead be allocated to the A-5
Certificates, in reduction of the Class A-5 Principal Balance, and all interest
losses (other than Allocated Realized Losses allocated to the Underlying
Certificates by Pro Rata Allocation) that would otherwise be allocated to the
Class A-4 and Class A-7 Certificates pursuant to clause (ii) of this paragraph


                                       5
<PAGE>

shall instead be allocated to the Class A-5 Certificates, in reduction of
accrued but unpaid interest thereon, and then in reduction of the Class A-5
Principal Balance.

         Allocated Realized Losses allocated to any Class of REMIC I Regular
Interests pursuant to this definition of "Allocated Realized Loss" in reduction
of the Class Principal Balance thereof shall also be allocated to the
Corresponding Class of Certificates in reduction of the Class Principal Balance
thereof by the same amount.

         The principal portion of any Allocated Realized Loss allocated to the
Class A-3-L Regular Interest on any Distribution Date pursuant to this
definition of "Allocated Realized Loss" shall be deemed "due for payment" on
such Distribution Date for purposes of the definitions of "Deficiency Amount"
and "Nonpayment."

         Allocated Uncompensated Interest Shortfall: For any Distribution Date,
the amount of Uncompensated Interest Shortfall (as defined in the Pooling and
Servicing Agreement) allocated to the Underlying Certificates on such
Distribution Date pursuant to the definition of "Uncompensated Interest
Shortfall" in the Pooling and Servicing Agreement.

         Allocated Uncompensated Interest Shortfall shall be allocated to the
REMIC I Regular Interests pro rata according to the amount of interest accrued
on each such Class during the immediately preceding accrual period, in reduction
thereof.

         Authenticating Agent: Any authenticating agent appointed by the Trustee
pursuant to Section 8.11.

         Authorized Denomination: With respect to the Class A-1, Class A-4,
Class A-5, Class A-6, Class A-7, Class A-8, Class A-12, Class A-13, Class A-15,
Class A-17, Class A-19 and Class A-20 Certificates, an initial Certificate
Principal Balance equal to $25,000 and multiples of $1 in excess thereof. With
respect to the Class A-2, Class A-10 and Class A-11 Certificates, an initial
Certificate Principal Balance equal to $1,000 and multiples of $1 in excess
thereof. With respect to the Class A-3 Certificates, an initial Certificate
Principal Balance equal to $1,000 and multiples of $1,000 in excess thereof.
With respect to the Class A-9, Class A-14, Class A-16 and Class A-18
Certificates, a Class Notional Amount as of the Closing Date equal to $100,000
and multiples of $1 in excess thereof. With respect to the Class R Certificates,
one Certificate with a Percentage Interest equal to 0.01% and one Certificate
with a Percentage Interest equal to 99.99%.

         Avoided Payment: Any amount previously distributed to an Owner on the
Insured Certificates that is recoverable and sought to be recovered as a
voidable preference by a trustee in bankruptcy pursuant to the United States
Bankruptcy Code (11 U.S.C.), as amended from time to time, in accordance with a
final nonappealable order of a court having competent jurisdiction.

         Bankruptcy Coverage: As defined in the Pooling and Servicing Agreement.

         Bankruptcy Loss: As defined in the Pooling and Servicing Agreement.

                                       6
<PAGE>

         Beneficial Holder: A Person holding a beneficial interest in any
Book-Entry Certificate as or through a DTC Participant or an Indirect DTC
Participant or a Person holding a beneficial interest in any Definitive
Certificate.

         Benefit Plan Opinion: With respect to any Certificate presented for
registration in the name of any Person, an Opinion of Counsel acceptable to and
in form and substance satisfactory to the Trustee and the Company to the effect
that the purchase or holding of such Certificate is permissible under applicable
law, will not constitute or result in a non-exempt prohibited transaction under
Section 406 of ERISA or Section 4975 of the Code, and will not subject the
Trust, the Trustee, the Delaware Trustee, the Certificate Administrator or the
Company to any obligation or liability (including obligations or liabilities
under Section 406 of ERISA or Section 4975 of the Code) in addition to those
undertaken in this Agreement, which Opinion of Counsel shall not be an expense
of the Trust, the Trustee, the Delaware Trustee, the Certificate Administrator
or the Company.

         Book-Entry Certificates: The Class A Certificates, beneficial ownership
and transfers of which shall be made through book entries as described in
Section 5.07.

         Business Day: Any day other than a Saturday, a Sunday, or a day on
which the Certificate Insurer (with respect to matters hereunder affecting the
Certificate Insurer) or on which banking institutions in Stockton, California,
Chicago, Illinois, New York, New York or Seattle, Washington or any city in
which the Corporate Trust Office is located are authorized or obligated by law
or executive order to be closed.

         Certificate: Any one of the Certificates issued pursuant to this
Agreement, executed by the Trustee and authenticated by or on behalf of the
Trustee hereunder in substantially one of the forms set forth in Exhibit A and B
hereto. The additional matter appearing in Exhibit H shall be deemed
incorporated into Exhibit A as though set forth at the end of such Exhibit.

         Certificate Account: The separate trust account created and maintained
with the Trustee, the Investment Depository or any other bank or trust company
acceptable to the Rating Agencies which is incorporated under the laws of the
United States or any state thereof pursuant to Section 3.04, which account shall
bear a designation clearly indicating that the funds deposited therein are held
in trust for the benefit of the Trust or any other account serving a similar
function acceptable to the Rating Agencies. Funds deposited in the Certificate
Account (exclusive of the Certificate Administrator Fee) shall be held in trust
for the Certificateholders and for the uses and purposes set forth in Section
2.01, Section 3.04, Section 3.05, Section 4.01 and Section 4.04.

         Certificate Administrator: The Company, or any successor thereto
appointed as provided pursuant to Section 7.02, acting to administer the
Certificates pursuant to Section 3.01.

         Certificate Administrator Fee: The monthly fee charged by the
Certificate Administrator for performing its duties hereunder, equal to, for
each Distribution Date, the product of (i) 1/12th of 0.015% and (ii) the
aggregate Class Principal Balance of the Certificates.

         Certificateholder or Holder: With respect to the Certificates, the
person in whose name a Certificate is registered in the Certificate Register,
except that, solely for the purposes of giving any consent pursuant to this


                                       7
<PAGE>

Agreement, any Certificate registered in the name of the Company, the
Certificate Administrator or any affiliate thereof shall be deemed not to be
outstanding and the Percentage Interest evidenced thereby shall not be taken
into account in determining whether the requisite percentage of Percentage
Interests necessary to effect any such consent has been obtained; provided, that
the Trustee may conclusively rely upon an Officer's Certificate to determine
whether any Person is an affiliate of the Company or the Certificate
Administrator. For so long as no Certificate Insurer Default exists (and whether
or not any payments with respect to Deficiency Amounts or Avoided Payments have
been made), the Certificate Insurer shall be deemed to be the sole Holder of all
outstanding Insured Certificates (other than the right to receive distributions
on such Insured Certificates, except as provided in Section 3.21); provided,
that the Certificate Insurer shall have no power without the consent of the
Owner of each Certificate affected thereby to: (i) reduce in any manner the
amount of, or delay the timing of, distributions of principal or interest
required to be made hereunder or reduce the Certificateholder's Percentage
Interest, the Certificate Interest Rate or the Termination Payment with respect
to the Insured Certificates; (ii) reduce the percentage of Percentage Interests
specified in Section 10.01 which are required to amend this Agreement; (iii)
create or permit the creation of any lien against any part of the Trust Assets,
the REMIC I Assets or the REMIC II Assets; (iv) modify any provision in any way
which would permit an earlier retirement of the Certificates; or (v) amend this
definition of "Certificateholder or Holder." With respect to the REMIC I Regular
Interests, the owner of the REMIC I Regular Interests, which as of the Closing
Date shall be the Trust.

         Certificate Insurance Policy: The Certificate Guaranty Insurance Policy
No. CA00859A issued by the Certificate Insurer in respect of the Class A-3
Certificates, a copy of which is attached hereto as Exhibit K.

         Certificate Insurer: XL Capital Assurance Inc., a New York stock
insurance corporation, or its successors in interest.

         Certificate Insurer Default: The existence and continuance of any of
the following: (a) a failure by the Certificate Insurer to make a payment
required under the Certificate Insurance Policy in accordance with its terms;
(b) the entry of a decree or order of a court or agency having jurisdiction in
respect of the Certificate Insurer in an involuntary case under any present or
future federal or state bankruptcy, insolvency or similar law appointing a
conservator or receiver or liquidator or other similar official of the
Certificate Insurer or of any substantial part of its property, or the entering
of an order for the winding up or liquidation of the affairs of the Certificate
Insurer and the continuance of any such decree or order undischarged or unstayed
and in force for a period of 90 consecutive days; (c) the Certificate Insurer
shall consent to the appointment of a conservator or receiver or liquidator or
other similar official in any insolvency, readjustment of debt, marshaling of
assets and liabilities or similar proceedings of or relating to the Certificate
Insurer or of or relating to all or substantially all of its property; or (d)
the Certificate Insurer shall admit in writing its inability to pay its debts
generally as they become due, file a petition to take advantage of or otherwise
voluntarily commence a case or proceeding under any applicable bankruptcy,
insolvency, reorganization or other similar statute, make an assignment for the
benefit of its creditors, or voluntarily suspend payment of its obligations.

         Certificate Insurer Premium: The "Premium," with respect to the Class
A-3 Certificates, as set forth in Section 3.03 of the Insurance Agreement.



                                       8
<PAGE>

         Certificate Interest Rate: For each Class of Certificates and REMIC I
Regular Interests, the per annum rate set forth as the Certificate Interest Rate
for such Class in the Preliminary Statement hereto.

         Certificate of Trust: The certificate of trust filed by the Delaware
Trustee with respect to the Trust with the Secretary of State in accordance with
Section 3810(a) of the Statutory Trust Statute.

         Certificate Principal Balance: For each Certificate of any Class, the
portion of the related Class Principal Balance, if any, represented by such
Certificate.

         Certificate Register and Certificate Registrar: The register maintained
and the registrar appointed, respectively, pursuant to Section 5.03.

         Class: All REMIC I Regular Interests or the Class R-1 Residual Interest
having the same priority and rights to payments on the Underlying Certificates
from the REMIC I Available Distribution Amount and all REMIC II Regular
Interests or the Class R-2 Residual Interest having the same priority and rights
to payments on the REMIC I Regular Interests from the REMIC II Available
Distribution Amount, as applicable, which REMIC I Regular Interests, REMIC II
Regular Interests and Class R Residual Interests, as applicable, shall be
designated as a separate Class, and which, in the case of the Certificates
(including the Class R Certificates representing ownership of the Class R
Residual Interests), shall be set forth in the applicable forms of Certificates
attached hereto as Exhibits A and B. Each Class of REMIC I Regular Interests and
the Class R-1 Residual Interest shall be entitled to receive the amounts
allocated to such Class pursuant to the definition of "REMIC I Distribution
Amount" only to the extent of the REMIC I Available Distribution Amount for such
Distribution Date remaining after distributions in accordance with prior clauses
of the definition of "REMIC I Distribution Amount" and each Class of REMIC II
Regular Interests and the Class R-2 Residual Interest shall be entitled to
receive the amounts allocated to such Class pursuant to the definition of "REMIC
II Distribution Amount" only to the extent of the REMIC II Available
Distribution Amount for such Distribution Date remaining after distributions in
accordance with prior clauses of the definition of "REMIC II Distribution
Amount."

         Class A Certificates: The Class A-1, Class A-2, Class A-3, Class A-4,
Class A-5, Class A-6, Class A-7, Class A-8, Class A-9, Class A-10, Class A-11,
Class A-12, Class A-13, Class A-14, Class A-15, Class A-16, Class A-17, Class
A-18, Class A-19 and Class A-20 Certificates.

         Class A-L Regular Interests: The Class A-1-L, Class A-2-L, Class A-3-L,
Class A-4-L, Class A-5-L, Class A-6-L, Class A-7-L, Class A-8-L, Class A-10-L,
Class A-11-L, Class A-12-L, Class A-13-L, Class A-15-L, Class A-17-L, Class
A-19-L and Class A-20-L Regular Interests.

         Class A-1 Certificates: The Certificates designated as "Class A-1" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-1-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.



                                       9
<PAGE>

         Class A-2 Certificates: The Certificates designated as "Class A-2" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-2-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-3 Certificates: The Certificates designated as "Class A-3" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-3 Covered Shortfall Amount: For any Distribution Date, the
amount of Allocated Uncompensated Interest Shortfall, if any, for such
Distribution Date that is allocated to the Class A-3-L Regular Interest on such
Distribution Date pursuant to the definition of "Allocated Uncompensated
Interest Shortfall," other than the portion thereof representing Curtailment
Shortfall (as defined in the Pooling and Servicing Agreement).

         Class A-3 Priority Amount: For any Distribution Date before March 2007,
zero; and for any Distribution Date in or after March 2007, $15,000.

         Class A-3 Reimbursement Amount: The sum of (a) all amounts previously
paid by the Certificate Insurer under the Certificate Insurance Policy which
have not been previously reimbursed and (b) interest on the foregoing at the
Late Payment Rate from the date such amount was paid by the Certificate Insurer
until paid in full.

         Class A-3 Reserve Fund: The separate trust account maintained by the
Certificate Administrator and held by the Trustee pursuant to Section 3.16,
which account shall bear a designation clearly indicating that the funds
deposited therein are held in trust for the benefit of the Trust on behalf of
the Class A-3 Certificateholders, or any other account serving a similar
function acceptable to the Rating Agencies and the Certificate Insurer, and
which account provides that the Trustee may make, or cause to be made,
withdrawals therefrom in accordance with Section 3.16.

         Class A-3-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-4 Certificates: The Certificates designated as "Class A-4" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-4-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-5 Certificates: The Certificates designated as "Class A-5" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-5-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-6 Certificates: The Certificates designated as "Class A-6" on
the face thereof in substantially the form attached hereto as Exhibit A.



                                       10
<PAGE>

         Class A-6 Priority Amount: For any Distribution Date before March 2007,
zero; and for any Distribution Date in or after March 2007, $245.45.

         Class A-6-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-7 Certificates: The Certificates designated as "Class A-7" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-7-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-8 Certificates: The Certificates designated as "Class A-8" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-8-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-9 Certificates: The Certificates designated as "Class A-9" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-9 Notional Amount: For any Distribution Date, the Class A-8
Principal Balance immediately before such Distribution Date.

         Class A-10 Certificates: The Certificates designated as "Class A-10" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-10-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-11 Certificates: The Certificates designated as "Class A-11" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-11-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-12 Certificates: The Certificates designated as "Class A-12" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-12-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-13 Certificates: The Certificates designated as "Class A-13" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-13-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.



                                       11
<PAGE>

         Class A-14 Certificates: The Certificates designated as "Class A-14" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-14 Notional Amount: For any Distribution Date, the Class A-13
Principal Balance immediately before such Distribution Date.

         Class A-15 Certificates: The Certificates designated as "Class A-15" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-15-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-16 Certificates: The Certificates designated as "Class A-16" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-16 Notional Amount: For any Distribution Date, the Class A-15
Principal Balance immediately before such Distribution Date multiplied by
75/550.

         Class A-17 Certificates: The Certificates designated as "Class A-17" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-17-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class A-18 Certificates: The Certificates designated as "Class A-18" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-18 Notional Amount: For any Distribution Date, the Class A-17
Principal Balance immediately before such Distribution Date multiplied by 5/550.

         Class A-19 Accretion Termination Date: The earlier to occur of (i) the
Distribution Date on which the Class A-17 Principal Balance has been reduced to
zero and (ii) the Credit Support Depletion Date.

         Class A-19 Accrual Amount: For any Distribution Date, an amount equal
to the amounts that would be payable to the Class A-19-L Regular Interest as
interest on such Distribution Date pursuant to clauses (I)(i) and (I)(ii)(a) of
the definition of "REMIC I Distribution Amount" without regard to the provisos
in such clauses. Notwithstanding the foregoing, for any Distribution Date after
the Class A-19 Accretion Termination Date, the Class A-19 Accrual Amount shall
be zero.

         Class A-19 Certificates: The Certificates designated as "Class A-19" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-19-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.



                                       12
<PAGE>

         Class A-20 Accretion Termination Date: The earlier to occur of (i) the
Distribution Date on which the Class A-17 and Class A-19 Principal Balances have
each been reduced to zero and (ii) the Credit Support Depletion Date.

         Class A-20 Accrual Amount: For any Distribution Date, an amount equal
to the amounts that would be payable to the Class A-20-L Regular Interest as
interest on such Distribution Date pursuant to clauses (I)(i) and (I)(ii)(a) of
the definition of "REMIC I Distribution Amount" without regard to the provisos
in such clauses. Notwithstanding the foregoing, for any Distribution Date after
the Class A-20 Accretion Termination Date, the Class A-20 Accrual Amount shall
be zero.

         Class A-20 Certificates: The Certificates designated as "Class A-20" on
the face thereof in substantially the form attached hereto as Exhibit A.

         Class A-20-L Regular Interest: The uncertificated undivided beneficial
interest in REMIC I which constitutes a REMIC I Regular Interest and is entitled
to distributions as set forth herein.

         Class B Certificates: The WaMu Mortgage Pass-Through Certificates,
Series 2003-S11, Class B-1, Class B-2, Class B-3, Class B-4, Class B-5 and Class
B-6, issued by the Underlying Trust pursuant to the Pooling and Servicing
Agreement.

         Class Notional Amount: With respect to any of the Class A-9, Class
A-14, Class A-16 and Class A-18 Certificates, the related notional amount for
such Class, as specified herein (e.g., the "Class Notional Amount" for the Class
A-9 Certificates is the Class A-9 Notional Amount).

         Class Principal Balance: For any Class of Certificates or REMIC I
Regular Interests and for the Class R-1 Residual Interest, the applicable
initial Class Principal Balance therefor set forth in the Preliminary Statement
hereto (or, in the case of the Class R Certificates, the Class Principal Balance
of the Class R-1 Residual Interest), corresponding to the rights of such Class
in payments of principal due to be passed through to the Certificateholders or
the Holders of the REMIC I Regular Interests from principal payments on the
Mortgage Loans, or the REMIC I Regular Interests, as applicable, as reduced from
time to time by (x) distributions of principal (including any Class A-19 or
Class A-20 Accrual Amount) to the Certificateholders or the Holders of the REMIC
I Regular Interests of such Class and (y) the portion of Allocated Realized
Losses allocated to the Class Principal Balance of such Class pursuant to the
definition of "Allocated Realized Loss" with respect to a given Distribution
Date. For any Distribution Date, the reduction of the Class Principal Balance of
any Class of Certificates and REMIC I Regular Interests pursuant to the
definition of "Allocated Realized Loss" shall be deemed effective after the
determination and distribution of principal on such Class pursuant to the
definitions of "REMIC I Distribution Amount" and "REMIC II Distribution Amount."

         For the Underlying Certificates or the Class B Certificates the
respective "Class Principal Balance" thereof as defined in the Pooling and
Servicing Agreement.

         Notwithstanding the foregoing, any amounts distributed in respect of
principal losses pursuant to paragraph (I)(v) of the definition of "REMIC I
Distribution Amount" shall not cause a reduction in the Class Principal Balances
of the REMIC I Regular Interests or their Corresponding Classes.



                                       13
<PAGE>

         In addition to the foregoing, on each Distribution Date (i) on or
before the Class A-19 Accretion Termination Date, the Class Principal Balance of
each of the Class A-19 Certificates and the Class A-19-L Regular Interest shall
be increased by the Class A-19 Accrual Amount for such Distribution Date and
(ii) on or before the Class A-20 Accretion Termination Date, the Class Principal
Balance of each of the Class A-20 Certificates and the Class A-20-L Regular
Interest shall be increased by the Class A-20 Accrual Amount for such
Distribution Date.

         The Class Principal Balance for the Class A-1 Certificates shall be
referred to as the "Class A-1 Principal Balance," the Class Principal Balance
for the Class A-1-L Regular Interest shall be referred to as the "Class A-1-L
Principal Balance" and so on. The Class Principal Balances for the Class A-9
Certificates, the Class A-14 Certificates, the Class A-16 Certificates and the
Class A-18 Certificates shall each be zero.

         Exclusively for the purpose of determining any subrogation rights of
the Certificate Insurer arising under Section 3.21 hereof, the "Class Principal
Balance" of the Class A-3 Certificates shall not be reduced by the amount of any
payments made by the Certificate Insurer in respect of principal on such
Certificates under the Certificate Insurance Policy, except to the extent such
payments have been reimbursed to the Certificate Insurer pursuant to the
provisions of this Agreement.

         Class R Certificates: The Certificates designated as "Class R" on the
face thereof in substantially the form attached hereto as Exhibit B,
representing ownership of the Class R-1 and Class R-2 Residual Interests, each
of which Class of Residual Interests has been designated as the sole class of
"residual interest" in REMIC I and REMIC II, respectively, pursuant to Section
2.06, Section 2.11 and Section 2.14, respectively, for purposes of Section
860G(a)(2) of the Code.

         Class R Residual Interests: The Class R-1 and Class R-2 Residual
Interests (which shall be transferable only as a unit evidenced by the Class R
Certificates, in accordance with the applicable provisions of Section 5.01).

         Class R-1 Residual Interest: The uncertificated undivided beneficial
interest in REMIC I which has been designated as the single class of "residual
interest" in REMIC I pursuant to Section 2.06. The Class R-1 Residual Interest,
together with the REMIC I Regular Interests, shall be deemed to be a separate
series of beneficial interests in the assets of the Trust consisting of the
REMIC I Assets pursuant to Section 3806(b)(2) of the Statutory Trust Statute.

         Class R-2 Residual Interest: The uncertificated undivided beneficial
interest in REMIC II which has been designated as the single class of "residual
interest" in REMIC II pursuant to Section 2.11. The Class R-2 Residual Interest,
together with the REMIC II Regular Interests, shall be deemed to be a separate
series of beneficial interests in the assets of the Trust consisting of the
REMIC II Assets pursuant to Section 3806(b)(2) of the Statutory Trust Statute.

         Clean-Up Call Percentage: 10%.

         Clearing Agency: An organization registered as a "clearing agency"
pursuant to Section 17A of the Securities Exchange Act of 1934, as amended,
which initially shall be DTC.

                                       14
<PAGE>

         Closing Date: February 26, 2004 which is the date of settlement of the
sale of the Certificates to the original purchasers thereof.

         Code: The Internal Revenue Code of 1986, as amended.

         Company: Washington Mutual Mortgage Securities Corp., a Delaware
corporation, or its successor-in-interest.

         Corporate Trust Office: The corporate trust office of the Trustee, at
which at any particular time its corporate trust business with respect to this
Agreement shall be administered, which office at the date of the execution of
this Agreement is located at 111 Wall Street, 14th Floor, Zone 3, New York, New
York 10005, Attention: Structured Finance Group, Washington Mutual 2004-RS1.

         Corporation: Any Person (other than an individual, partnership, joint
venture or unincorporated organization) incorporated, associated, organized,
chartered or existing under the laws of any state or under the federal laws of
the United States of America; provided, that such Person have indefinite
existence under the law of its domicile.

         Corresponding Class: With respect to the Certificates and the REMIC I
Regular Interests, the "Corresponding Class" shall be as indicated in the
following table:

Class A-1-L                    Class A-1
Class A-2-L                    Class A-2
Class A-3-L                    Class A-3
Class A-4-L                    Class A-4
Class A-5-L                    Class A-5
Class A-6-L                    Class A-6
Class A-7-L                    Class A-7
Class A-8-L                    Class A-8
Class A-10-L                   Class A-10
Class A-11-L                   Class A-11
Class A-12-L                   Class A-12
Class A-13-L                   Class A-13
Class A-15-L                   Class A-15
Class A-17-L                   Class A-17
Class A-19-L                   Class A-19
Class A-20-L                   Class A-20



         Credit Support Depletion Date: The first Distribution Date on which the
aggregate Class Principal Balance of the Class B Certificates has been or will
be reduced to zero.

         Cut-Off Date: October 1, 2003.

         Deceased Holder: A Beneficial Holder of a Special Retail Certificate
who was living at the time such Certificate was acquired and whose authorized
personal representative, surviving tenant by the entirety, surviving joint


                                       15
<PAGE>

tenant or surviving tenant in common or other person empowered to act on behalf
of such Beneficial Holder causes to be furnished to DTC evidence of such
Beneficial Holder's death satisfactory to the Trustee and any tax waivers
requested by the Trustee.

         Deficiency Amount: Any portion of a Scheduled Payment that shall become
due for payment but shall be unpaid by reason of Nonpayment.

         Definitive Certificates: Certificates in definitive, fully registered
and certificated form.

         Delaware Trustee: Christiana Bank & Trust Company, or its
successor-in-interest as provided in Section 8.09, or any successor trustee
appointed as herein provided.

         Depositary Agreement: The Letter of Representations, dated February 25,
2004 by and among DTC, the Trust and the Trustee. The Trustee is authorized to
enter into the Depositary Agreement on behalf of the Trust.

         Determination Date: As defined in the Pooling and Servicing Agreement.

         Disqualified Organization: Any Person which is not a Permitted
Transferee, but does not include any Pass-Through Entity which owns or holds a
Residual Certificate and of which a Disqualified Organization, directly or
indirectly, may be a stockholder, partner or beneficiary.

         Distribution Date: With respect to distributions on the Underlying
Certificates, the REMIC I Regular Interests and the Certificates, the 25th day
(or, if such 25th day is not a Business Day, the Business Day immediately
succeeding such 25th day) of each month, with the first such date being March
25, 2004.

         DTC: The Depository Trust Company.

         DTC Participant: A broker, dealer, bank, other financial institution or
other Person for whom DTC effects book-entry transfers and pledges of securities
deposited with DTC.

         Eligible Institution: An institution having (i) the highest short-term
debt rating, and one of the two highest long-term debt ratings of the Rating
Agencies or (ii) the approval of the Rating Agencies.

         ERISA: The Employee Retirement Income Security Act of 1974, as amended.

         Event of Default: Any event of default as specified in Section 7.01.

         FDIC: Federal Deposit Insurance Corporation, or any successor thereto.

         Final Maturity Date: With respect to each Class of the REMIC I Regular
Interests and the Certificates, the date set forth in the applicable table
contained in the Preliminary Statement hereto.

         Fitch: Fitch Ratings, provided that at any time it be a Rating Agency.

         Fraud Coverage: As defined in the Pooling and Servicing Agreement.

                                       16
<PAGE>

         Fraud Loss: As defined in the Pooling and Servicing Agreement.

         Freddie Mac: The entity formerly known as the Federal Home Loan
Mortgage Corporation, or any successor thereto.

         Indirect DTC Participants: Entities such as banks, brokers, dealers or
trust companies, that clear through or maintain a custodial relationship with a
DTC Participant, either directly or indirectly.

         Insurance Agreement: The Insurance Agreement, dated as of February 26,
2004, among the Certificate Insurer, the Trustee and the Company.

         Insured Certificates: The Class A-3 Certificates.

         Insured Payment: With respect to the Insured Certificates, (i) as of
any Distribution Date, any Deficiency Amount and (ii) any Avoided Payment.

         Interest Distribution Amount: For any Distribution Date, for any Class
of the REMIC I Regular Interests and the Class R-1 Residual Interest, the amount
of interest accrued during the Prior Period (or, in the case of the Class A-8-L
and Class A-13-L Regular Interests, during the period beginning on the 25th day
of the preceding calendar month and ending on the 24th day of the month of the
Distribution Date), at the related Certificate Interest Rate for such Class for
such Distribution Date, on the respective Class Principal Balance immediately
before such Distribution Date, reduced by Allocated Uncompensated Interest
Shortfall and the interest portion of Allocated Realized Losses allocated to
such Class pursuant to the definitions of "Allocated Uncompensated Interest
Shortfall" and "Allocated Realized Loss," respectively. The computation of
interest accrued shall be made on the basis of a 360-day year of twelve 30-day
months. The Interest Distribution Amounts for the Class A-6-L and Class A-12-L
Regular Interests shall equal zero.

         Investment Depository: JPMorgan Chase Bank, or another bank or trust
company designated from time to time by the Certificate Administrator. The
Investment Depository shall at all times be an Eligible Institution.

         Last Scheduled Distribution Date: With respect to any Class of
Certificates, the Final Maturity Date for such Class.

         Late Payment Rate: The lesser of (a) the greater of (i) the prime rate
as published in the Wall Street Journal (or if no such rate is published
thereby, in a publication selected by the Insurer) (any change in such rate of
interest to be effective on the date such change is published) plus 2%, and (ii)
5.50%, and (b) the maximum rate permissible under applicable usury or similar
laws limiting interest rates. The Late Payment Rate shall be computed on the
basis of the actual number of days elapsed over a year of 360 days. The Late
Payment Rate shall be calculated by the Insurer and evidenced by a certificate
of the Certificate Insurer delivered to the Trustee.

         LIBOR: With respect to the first Distribution Date, 1.100%; and with
respect to each Distribution Date thereafter, the London Interbank Offered Rate
for one-month United States dollar deposits determined by the Certificate


                                       17
<PAGE>

Administrator on the LIBOR Determination Date on the basis of quotations
provided by each of the Reference Banks as of approximately 11:00 a.m. (London
time) on the LIBOR Determination Date as such quotations appear on The Bloomberg
Professional Service, as follows:

         (A) in the event that only one or none of the Reference Banks provides
such quotations, the higher of:

         (i) LIBOR as determined on the immediately preceding LIBOR
Determination Date (or, in the case of the first LIBOR Determination Date,
1.100%), and

         (ii) the Reserve Rate. The "Reserve Rate" will be the rate per annum
(rounded upward, if necessary, to the nearest multiple of 1/16th of 1%) that the
Certificate Administrator determines to be either

         (x) the arithmetic mean of the offered quotations that the leading
banks in New York City selected by the Certificate Administrator in its sole
discretion are then quoting on the relevant LIBOR Determination Date for
one-month United States dollar deposits to the principal London office of each
of the Reference Banks or those of them (being at least two in number) to which
such offered quotations are, in the opinion of the Certificate Administrator,
being so made, or

         (y) in the event that the Certificate Administrator can determine no
such arithmetic mean, the arithmetic mean of the offered quotations that the
leading banks in New York City selected by the Certificate Administrator in its
sole discretion are quoting on such LIBOR Determination Date to leading European
banks for one-month United States dollar deposits, provided, however, that if
the banks selected by the Certificate Administrator are not then so quoting,
LIBOR shall be as determined on the immediately preceding LIBOR Determination
Date (or, in the case of the first LIBOR Determination Date, 1.100%);

         (B) otherwise, the arithmetic mean (rounded upward, if necessary, to
the nearest multiple of 1/16th of 1%) of such offered quotations

the establishment of which, in each case, shall be final and binding in the
absence of manifest error.

         LIBOR Determination Date: With respect to interest paid on any
Distribution Date, the second day on which banks in London and New York City are
open for the transaction of international business prior to the 25th day of the
month preceding the Distribution Date.

         Living Holder: A Beneficial Holder of a Special Retail Certificate
other than a Deceased Holder.



                                       18
<PAGE>

         Lockout Percentage: For any Distribution Date, the product of (i) the
aggregate Class Principal Balance of the Class A-4 and Class A-5 Certificates
divided by the aggregate Class Principal Balance of the Certificates, in each
case immediately before such Distribution Date and (ii) the Step Down
Percentage.

         Lockout Priority Amount: For any Distribution Date, the product of (i)
the Lockout Percentage and (ii) the Principal Distribution Amount for that
Distribution Date.

         Master Servicer:  As defined in the Pooling and Servicing Agreement.

         Mortgage Loan Schedule: The schedule, as amended from time to time, of
Mortgage Loans attached as Exhibit D to the Pooling and Servicing Agreement.

         Mortgage Loans: The mortgage loans and cooperative loans (if any)
listed on the Mortgage Loan Schedule attached as Exhibit D to the Pooling and
Servicing Agreement and transferred and assigned to the Underlying Trust
pursuant to the Pooling and Servicing Agreement.

         Nonpayment: With respect to any Distribution Date, the failure of the
Trustee to receive in full, in accordance with the terms of this Agreement
(without regard, on any Distribution Date other than the Distribution Dates
described in the second and third sentences of the definition of "Scheduled
Payment," to the Trustee's receipt of the Principal Distribution Amount), any
Scheduled Payment that is due for payment with respect to such Distribution
Date.

         Non-U.S. Person: A Person that is not a U.S. Person.

         Notice: With respect to the Insured Certificates, the notice
substantially in the form of Exhibit A attached to the Certificate Insurance
Policy, the original of which is subsequently delivered by registered or
certified mail, from the Trustee specifying the Insured Payment which shall be
due and owing on the applicable Distribution Date.

         Notice Addresses: (a) In the case of the Company, 75 North Fairway
Drive, Vernon Hills, Illinois 60061, Attention: Master Servicing Department,
with a copy to: Washington Mutual Legal Department, 1201 Third Avenue, WMT 1706,
Seattle, WA 98101, Attention: WMMSC, or such other address as may hereafter be
furnished to the Trustee in writing by the Company, (b) in the case of the
Trustee, at its Corporate Trust Office, or such other address as may hereafter
be furnished to the Certificate Administrator in writing by the Trustee, (c) in
the case of the Delaware Trustee, 1314 King Street, Wilmington, DE 19801, or
such other address as may hereafter be furnished to the Certificate
Administrator in writing by the Delaware Trustee, (d) in the case of the Trust,
c/o Citibank, N.A., at the Corporate Trust Office, or such other address as may
hereafter be furnished to the Certificate Administrator in writing by the
Trustee, (e) in the case of the Certificate Registrar, at its Corporate Trust
Office, or such other address as may hereafter be furnished to the Trustee in
writing by the Certificate Registrar, (f) in the case of S&P, 55 Water Street,
41st Floor, New York, New York 10041-0003, Attention: Frank Raiter, or such
other address as may hereafter be furnished to the Trustee and Certificate
Administrator in writing by S&P, (g) in the case of Fitch, 1 State Street Plaza,
New York, New York 10004, Attention: Glenn Costello, or such other address as
may hereafter be furnished to the Trustee and Certificate Administrator in
writing by Fitch and (h) in the case of the Certificate Insurer, to XL Capital


                                       19
<PAGE>

Assurance Inc., 1221 Avenue of the Americas, New York, New York 10020, Attn:
Surveillance, or such other address as may hereafter be furnished to the Trustee
and Certificate Administrator in writing by the Certificate Insurer.

         OTS: The Office of Thrift Supervision, or any successor thereto.

         Officer's Certificate: A certificate signed by the Chairman of the
Board, the President, a Vice President, or the Treasurer of the Certificate
Administrator and delivered to the Trustee or the Delaware Trustee, as
applicable.

         Opinion of Counsel: A written opinion of counsel, who shall be
reasonably acceptable to the Trustee or the Delaware Trustee, as applicable, and
who may be counsel (including in-house counsel) for the Company or the
Certificate Administrator.

         Original Trust Agreement: The Trust Agreement, dated as of February 1,
2004, between the Company and the Delaware Trustee, providing for the creation
of the Trust.

         Owner: Each Holder of an Insured Certificate who, on the applicable
Distribution Date, is entitled under the terms of the Insured Certificates to
payment thereunder.

         Ownership Interest: With respect to any Residual Certificate, any
ownership or security interest in such Residual Certificate, including any
interest in a Residual Certificate as the Holder thereof and any other interest
therein whether direct or indirect, legal or beneficial, as owner or as pledgee.

         Pass-Through Entity: Any regulated investment company, real estate
investment trust, common trust fund, partnership, trust or estate, and any
organization to which Section 1381 of the Code applies.

         Paying Agent: Any paying agent appointed by the Trustee pursuant to
Section 8.12.

         Percentage Interest: (a) With respect to the right of each Certificate
of a particular Class in the distributions allocated to such Class, "Percentage
Interest" shall mean the percentage equal to:

         (i) with respect to any Certificate (other than the Residual, Class
A-9, Class A-14, Class A-16 and Class A-18 Certificates), its Certificate
Principal Balance divided by the applicable Class Principal Balance;

         (ii) with respect to any Class A-9, Class A-14, Class A-16 or Class
A-18 Certificate, the portion of the respective Class Notional Amount evidenced
by such Certificate divided by the respective Class Notional Amount; and

         (iii) with respect to any Residual Certificate, the percentage set
forth on the face of such Certificate.



                                       20
<PAGE>

         (b) With respect to the rights of each Certificate in connection with
Sections 5.09, 7.01, 8.01(c), 8.02, 8.07, 10.01 and 10.03, "Percentage Interest"
shall mean the percentage equal to:

         (i) with respect to any Certificate (other than the Class A-9, Class
A-14, Class A-16, Class A-18 and Residual Certificates), the product of (x)
ninety-six percent (96%) and (y) its Certificate Principal Balance divided by
the Aggregate Certificate Principal Balance of the Certificates; provided,
however, that the percentage in clause (x) above shall be increased by one
percent (1%) upon the retirement of each Class of Certificates referenced in the
parenthetical above (other than the Residual Certificates);

         (ii) with respect to any Class A-9, Class A-14, Class A-16 or Class
A-18 Certificate, one percent (1%) of such Certificate's Percentage Interest as
calculated by paragraph (a)(ii) of this definition; and

         (iii) with respect to any Residual Certificate, zero.

         Permitted Transferee: With respect to the holding or ownership of any
Residual Certificate, any Person other than (i) the United States, a State or
any political subdivision thereof, or any agency or instrumentality of any of
the foregoing, (ii) a foreign government, International Organization or any
agency or instrumentality of either of the foregoing, (iii) an organization
(except certain farmers' cooperatives described in Code Section 521) which is
exempt from the taxes imposed by Chapter 1 of the Code (unless such organization
is subject to the tax imposed by Section 511 of the Code on unrelated business
taxable income), (iv) rural electric and telephone cooperatives described in
Code Section 1381(a)(2)(C), (v) any "electing large partnership" as defined in
Section 775(a) of the Code, (vi) any Person from whom the Trustee has not
received an affidavit to the effect that it is not a "disqualified organization"
within the meaning of Section 860E(e)(5) of the Code, and (vii) any other Person
so designated by the Company based upon an Opinion of Counsel that the transfer
of an Ownership Interest in a Residual Certificate to such Person may cause
REMIC I or REMIC II to fail to qualify as a REMIC at any time that the
Certificates are outstanding. The terms "United States," "State" and
"International Organization" shall have the meanings set forth in Code Section
7701 or successor provisions. A corporation shall not be treated as an
instrumentality of the United States or of any State or political subdivision
thereof if all of its activities are subject to tax, and, with the exception of
the Freddie Mac, a majority of its board of directors is not selected by such
governmental unit.

         Person: Any individual, corporation, limited liability company,
partnership, joint venture, association, joint-stock company, trust,
unincorporated organization or government or any agency or political subdivision
thereof.

         Planned Principal Balance: With respect to the Class A-15 Certificates,
the amount set forth in the table attached as Appendix D to the Prospectus, for
the applicable Distribution Date, under the heading "Class A-15 Planned
Principal Balance."

         Pooling and Servicing Agreement: The Pooling and Servicing Agreement,
dated as of October 1, 2003, by and among the Company, as Depositor and Master
Servicer, the Trustee and the Delaware Trustee, relating to the WaMu Mortgage
Pass-Through Certificates Series 2003-S11 Trust.

                                       21
<PAGE>

         Principal Balance: As defined in the Pooling and Servicing Agreement.

         Principal Distribution Amount: For any Distribution Date, an amount
equal to the portion of the REMIC I Available Distribution Amount for that
Distribution Date remaining after the distributions pursuant to clause (I)(i)
and (I)(ii) or clause (II)(i) and (II)(ii), as applicable, of the definition of
"REMIC I Distribution Amount."

         Prior Period: With respect to any Distribution Date, the calendar month
immediately preceding such Distribution Date.

     Pro Rata Allocation: As defined in the Pooling and Servicing Agreement.

         Prospectus: The Prospectus, dated February 10, 2004, and the Prospectus
Supplement, dated February 24, 2004, of the Company.

         Random Lot: With respect to any Distribution Date on which a mandatory
distribution is to be made on the Special Retail Certificates (as described in
Section 4.05), the method by which DTC will determine which Special Retail
Certificates will be paid principal, using its established random lot procedures
or, if such Certificates are no longer represented by a Book-Entry Certificate,
using the Trustee's procedures.

         Rating Agency: Initially, each of S&P and Fitch and thereafter, each
nationally recognized statistical rating organization that has rated the
Certificates at the request of the Company, or their respective successors in
interest.

         Ratings: As of any date of determination, the ratings, if any, of the
Certificates as assigned by the applicable Rating Agencies (determined in the
case of the Insured Certificates, without giving effect to the Certificate
Insurance Policy).

         Record Date: The last Business Day of the month immediately preceding
the month of the related Distribution Date.

         Reference Banks: Barclays Bank PLC, Deutsche Bank and JPMorgan Chase
Bank or, if any such bank shall cease to provide quotations for one-month United
States dollar deposits, any other leading bank with an established place of
business in London engaged in transactions in Eurodollar deposits in the
international Eurocurrency market not controlling, controlled by or under common
control with the Company, designated by the Company from time to time for the
purpose of providing quotations for one-month United States dollar-denominated
deposits.

         Regular Interests: (i) With respect to REMIC I, the REMIC I Regular
Interests and (iii) with respect to REMIC II, the REMIC II Regular Interests.

         REMIC: A real estate mortgage investment conduit, as such term is
defined in the Code.



                                       22
<PAGE>

         REMIC Provisions: Sections 860A through 860G of the Code, related Code
provisions and regulations promulgated thereunder, as the foregoing may be in
effect from time to time.

         REMIC I: The segregated pool of assets of the Trust consisting of the
REMIC I Assets, which shall be a REMIC pursuant to the Code, with respect to
which a separate REMIC election is to be made and the beneficial interests in
which shall be the REMIC I Regular Interests and the Class R-1 Residual
Interest.

         REMIC I Assets: All of the Trust Assets other than the Certificate
Insurance Policy and the Class A-3 Reserve Fund.

         REMIC I Available Distribution Amount: For any Distribution Date, the
amount distributed to the Underlying Certificates on that Distribution Date
pursuant to the Pooling and Servicing Agreement, reduced by the Certificate
Administrator Fee payable to the Certificate Administrator and the Certificate
Insurer Premium payable to the Certificate Insurer on such Distribution Date.

         REMIC I Distribution Amount: (I) For any Distribution Date prior to the
Credit Support Depletion Date, the REMIC I Available Distribution Amount shall
be distributed to the REMIC I Regular Interests, the Class R-1 Residual Interest
and the Certificate Insurer in the following amounts and priority, to the extent
of the REMIC I Available Distribution Amount for such Distribution Date:

         (i) first, to the REMIC I Regular Interests and the Class R-1 Residual
Interest, concurrently, the Interest Distribution Amounts for such Classes
remaining unpaid from previous Distribution Dates, pro rata according to their
respective shares of such unpaid amounts; provided, however, that (1) on or
before the Class A-19 Accretion Termination Date, the amount that would
otherwise be payable to the Class A-19-L Regular Interest pursuant to this
clause (I)(i) will be paid instead as principal as set forth in clause
(I)(ii)(b) of this definition of "REMIC I Distribution Amount" and (2) on or
before the Class A-20 Accretion Termination Date, the amount that would
otherwise be payable to the Class A-20-L Regular Interest pursuant to this
clause (I)(i) will be paid instead as principal as set forth in clause
(I)(ii)(c) of this definition of "REMIC I Distribution Amount";

         (ii) second,

         (a) to the REMIC I Regular Interests and the Class R-1 Residual
Interest, concurrently, the Interest Distribution Amounts for such Classes for
the current Distribution Date, pro rata according to their respective Interest
Distribution Amounts; provided, however, that (1) on or before the Class A-19
Accretion Termination Date, the amount that would otherwise be payable to the
Class A-19-L Regular Interest pursuant to this clause (I)(ii)(a) will be paid
instead as principal as set forth in clause (I)(ii)(b) of this definition of
"REMIC I Distribution Amount" and (2) on or before the Class A-20 Accretion
Termination Date, the amount that would otherwise be payable to the Class A-20-L
Regular Interest pursuant to this clause (I)(ii)(a) will be paid instead as
principal as set forth in clause (I)(ii)(c) of this definition of "REMIC I
Distribution Amount";



                                       23
<PAGE>

         (b) on or before the Class A-19 Accretion Termination Date, the Class
A-19 Accrual Amount, as principal, sequentially, as follows:

         (1) first, to the Class A-17-L Regular Interest, until the Class A-17-L
Principal Balance has been reduced to zero; and

         (2) second, to the Class A-19-L Regular Interest; and

         (c) on or before the Class A-20 Accretion Termination Date, the Class
A-20 Accrual Amount, as principal, as follows:

         (1) first, if the Class Principal Balance of the Underlying
Certificates for that Distribution Date is greater than the amount for that
Distribution Date set forth in the table attached as Appendix E to the
Prospectus, then, sequentially, as follows:

         (I) first, to the Class A-17-L Regular Interest, until the Class A-17-L
Principal Balance has been reduced to zero; and

         (II) second, to the Class A-19-L Regular Interest, until the Class
A-19-L Principal Balance has been reduced to zero; and

         (2) second, to the Class A-20-L Regular Interest; and

         (iii) third, to the REMIC I Regular Interests and the Class R-1
Residual Interest, as principal, the Principal Distribution Amount, first, to
the Class R-1 Residual Interest until the Class Principal Balance thereof has
been reduced to zero, and then, concurrently, as follows:

         (a) 0.2727274038% to the Class A-12-L Regular Interest, until the Class
A-12-L Principal Balance has been reduced to zero; and

         (b) 99.7272725962%, sequentially, as follows:

         (1) first, to the Class A-4-L and Class A-5-L Regular Interests, pro
rata, an amount, up to the amount of the Lockout Priority Amount for that
Distribution Date;

         (2) second, concurrently, as follows:

         (I) 48.3831335192%, sequentially, as follows:

         (A) first, to the Class A-3-L and Class A-6-L Regular Interests, pro
rata, an amount, up to the amount of the Class A-3 Priority Amount and the Class
A-6 Priority Amount, respectively, for that Distribution Date;

                                       24
<PAGE>

         (B) second, to the Class A-1-L and Class A-13-L Regular Interests, pro
rata, until the Class A-1-L and Class A-13-L Principal Balances have each been
reduced to zero;

         (C) third, to the Class A-2-L Regular Interest, until the Class A-2-L
Principal Balance has been reduced to zero; and

         (D) fourth, to the Class A-3-L and Class A-6-L Regular Interests, pro
rata, until the Class A-3-L and Class A-6-L Principal Balances have each been
reduced to zero;

         (II) 51.6168664808%, sequentially, as follows:

         (A) first, concurrently, as follows:

         (i) 40.9562321561%, to the Class A-7-L Regular Interest, until the
Class A-7-L Principal Balance has been reduced to zero;

         (ii) 32.8163661781%, sequentially, as follows:

         (1) first, to the Class A-15-L Regular Interest, the amount necessary
to reduce the Class A-15-L Principal Balance to its Planned Principal Balance
for that Distribution Date;

         (2) second, either:


         (I) if the Class Principal Balance of the Underlying Certificates for
that Distribution Date is less than or equal to the amount for that Distribution
Date set forth in the table attached as Appendix E to the Prospectus, then
sequentially, as follows:


         (A) first, to the Class A-20-L Regular Interest, until the Class A-20-L
Principal Balance has been reduced to zero;

                                       25
<PAGE>


         (B) second, to the Class A-17-L Regular Interest, until the Class
A-17-L Principal Balance has been reduced to zero; and


         (C) third, to the Class A-19-L Regular Interest, until the Class A-19-L
Principal Balance has been reduced to zero; or


         (II) if the Class Principal Balance of the Underlying Certificates for
that Distribution Date is greater than the amount for that Distribution Date set
forth in the table attached as Appendix E to the Prospectus, then sequentially,
as follows:


         (A) first, to the Class A-17-L Regular Interest, until the Class A-17-L
Principal Balance has been reduced to zero;


         (B) second, to the Class A-19-L Regular Interest, until the Class
A-19-L Principal Balance has been reduced to zero; and


         (C) third, to the Class A-20-L Regular Interest, until the Class A-20-L
Principal Balance has been reduced to zero; and

         (3) third, to the Class A-15-L Regular Interest (without regard to its
Planned Principal Balance), until the Class A-15-L Principal Balance has been
reduced to zero; and



                                       26
<PAGE>

         (iii) 26.2274016658% to the Class A-8-L Regular Interest, until the
Class A-8-L Principal Balance has been reduced to zero;

         (B) second, to the Class A-10-L Regular Interest, until the Class
A-10-L Principal Balance has been reduced to zero; and

         (C) third, to the Class A-11-L Regular Interest, until the Class A-11-L
Principal Balance has been reduced to zero; and

         (3) third, to the Class A-4-L and Class A-5-L Regular Interests, pro
rata, until the Class A-4-L and Class A-5-L Principal Balances have each been
reduced to zero.

         (iv) fourth, to the Certificate Insurer, the Class A-3 Reimbursement
Amount for such Distribution Date;

         (v) fifth, to each Class of Class A-L Regular Interests in order of
seniority, pro rata, the remaining portion, if any, of the REMIC I Available
Distribution Amount, up to the amount of unreimbursed Allocated Realized Losses
allocable to principal previously allocated or to be allocated on such
Distribution Date to such Class, if any; provided, that any amounts distributed
pursuant to this paragraph (I)(v) of this definition of "REMIC I Distribution
Amount" shall not cause a reduction in the Class Principal Balances of any of
the REMIC I Regular Interests; and

         (vi) sixth, to the Class R-1 Residual Interest, the Residual
Distribution Amounts for the REMIC I Regular Interests for such Distribution
Date.

         (II) For any Distribution Date on or after the Credit Support Depletion
Date, the REMIC I Available Distribution Amount for such Distribution Date shall
be distributed to the outstanding Classes of REMIC I Regular Interests, the
Class R-1 Residual Interest and the Certificate Insurer in the following amounts
and priority:

         (i) first, to the Class A-L Regular Interests, the amount payable to
each such Class of Regular Interests on prior Distribution Dates pursuant to
clause (I)(ii) or (II)(ii) of this definition of "REMIC I Distribution Amount,"
and remaining unpaid, pro rata according to such amount payable to the extent of
amounts available;

         (ii) second, to the Class A-L Regular Interests, concurrently, the
Interest Distribution Amounts for such Classes of Regular Interests for the
current Distribution Date, pro rata according to their respective Interest
Distribution Amounts;

         (iii) third, to the Class A-L Regular Interests, pro rata according to
Class Principal Balance, as principal, the Principal Distribution Amount;

                                       27
<PAGE>

         (iv) fourth, to the Certificate Insurer, the Class A-3 Reimbursement
Amount for such Distribution Date; and

         (v) fifth, to the Class R-1 Residual Interest, the Residual
Distribution Amount for the Class R-1 Residual Interest for such Distribution
Date.

         REMIC I Regular Interests: The Classes of undivided beneficial
interests in REMIC I designated as "regular interests" in the table titled
"REMIC I Interests" in the Preliminary Statement hereto. The REMIC I Regular
Interests, together with the Class R-1 Residual Interest, shall be deemed to be
a separate series of beneficial interests in the assets of the Trust consisting
of the REMIC I Assets pursuant to Section 3806(b)(2) of the Statutory Trust
Statute.

         REMIC II: The segregated pool of assets of the Trust consisting of the
REMIC II Assets, which shall be a REMIC pursuant to the Code, with respect to
which a separate REMIC election is to be made, and the beneficial interests in
which shall be the REMIC II Regular Interests and the Class R-2 Residual
Interest.

         REMIC II Assets: The REMIC I Regular Interests.

         REMIC II Available Distribution Amount: For any Distribution Date, the
aggregate of all distributions to the REMIC I Regular Interests (which amount
shall be available for distributions to the Certificates and the Class R-2
Residual Interest as provided herein).

         REMIC II Distribution Amount: The REMIC II Available Distribution
Amount for any Distribution Date shall be distributed to the Certificates and
the Class R-2 Residual Interest in the following amounts and priority, to the
extent of the REMIC II Available Distribution Amount for such Distribution Date:

         (i) to each Class of Certificates (other than the Class A-8, Class A-9,
Class A-13, Class A-14, Class A-15, Class A-16, Class A-17 and Class A-18
Certificates), the amounts (other than any Rounding Amount, Class A-3 Covered
Shortfall Amount or Deficiency Amount) distributed to its Corresponding Class on
such Distribution Date;

         (ii) (A) to the Class A-8, Class A-13, Class A-15 and Class A-17
Certificates, the amount distributed as principal to its Corresponding Class on
such Distribution Date, (B) to each Class of the Class A-8 and Class A-9
Certificates, the amount distributed as interest to the Class A-8-L Regular
Interest on such Distribution Date, pro rata according to, for each such Class,
the product of 1/12 of the Certificate Interest Rate for such Class and the
Class Principal Balance or Class Notional Amount, as applicable, for such Class
before allocating principal losses and giving effect to distributions of
principal on such Distribution Date, (C) to each Class of the Class A-13 and
Class A-14 Certificates, the amount distributed as interest to the Class A-13-L
Regular Interest on such Distribution Date, pro rata according to, for each such
Class, the product of 1/12 of the Certificate Interest Rate for such Class and
the Class Principal Balance or Class Notional Amount, as applicable, for such
Class before allocating principal losses and giving effect to distributions of
principal on such Distribution Date, (D) to each Class of the Class A-15 and
Class A-16 Certificates, the amount distributed as interest to the Class A-15-L
Regular Interest on such Distribution Date, pro rata according to, for each such
Class, the product of 1/12 of the Certificate Interest Rate for such Class and
the Class Principal Balance or Class Notional Amount, as applicable, for such
Class before allocating principal losses and giving effect to distributions of


                                       28
<PAGE>

principal on such Distribution Date and (E) to each Class of the Class A-17 and
Class A-18 Certificates, the amount distributed as interest to the Class A-17-L
Regular Interest on such Distribution Date, pro rata according to, for each such
Class, the product of 1/12 of the Certificate Interest Rate for such Class and
the Class Principal Balance or Class Notional Amount, as applicable, for such
Class before allocating principal losses and giving effect to distributions of
principal on such Distribution Date; and

         (iii) to the Class R-2 Residual Interest, the Residual Distribution
Amount for the Class R-2 Residual Interest for such Distribution Date.

         In each case where a distribution is required to be made concurrently
to two or more Classes of Certificates pursuant to this definition of "REMIC II
Distribution Amount," if the portion of the REMIC II Available Distribution
Amount from which such distribution is required to be made is insufficient to
make such distribution in full to such Classes, such distribution shall be
allocated between such Classes pro rata according to the respective amounts to
which they are otherwise entitled from such distribution.

         REMIC II Regular Interests: The Classes of undivided beneficial
interests in REMIC II designated as "regular interests" in the table titled
"REMIC II Interests" in the Preliminary Statement hereto. The REMIC II Regular
Interests, together with the Class R-2 Residual Interest, shall be deemed to be
a separate series of beneficial interests in the assets of the Trust consisting
of the REMIC II Assets pursuant to Section 3806(b)(2) of the Statutory Trust
Statute.

         Residual Certificates:  The Class R Certificates.

         Residual Distribution Amount: For any Distribution Date, with respect
to the Class R-1 Residual Interest, any portion of the REMIC I Available
Distribution Amount remaining after all distributions of the REMIC I Available
Distribution Amount pursuant to clauses (I)(i) through (v) and clauses (II)(i)
through (iv) of the definition of "REMIC I Distribution Amount."

         For any Distribution Date, with respect to the Class R-2 Residual
Interest, any portion of the REMIC II Available Distribution Amount remaining
after all distributions of such REMIC II Available Distribution Amount pursuant
to clauses (i) and (ii) of the definition of "REMIC II Distribution Amount."

         Upon termination of the obligations created by this Agreement and
liquidation of REMIC I and REMIC II, the amounts which remain on deposit in the
Certificate Account after payment to the Holders of the REMIC I Regular
Interests of the amounts set forth in Section 9.01 of this Agreement, and
subject to the conditions set forth therein, shall be distributed to the Class
R-1 and Class R-2 Residual Interests in accordance with the preceding sentences
of this definition as if the date of such distribution were a Distribution Date.

         Responsible Officer: When used with respect to the Trustee or the
Delaware Trustee, any officer assigned to and working in the Corporate Trust
Office (in the case of the Trustee) or its corporate trust office (in the case
of the Delaware Trustee) or, in each case, in a similar group having direct


                                       29
<PAGE>

responsibility for the administration of this Agreement and also, with respect
to a particular matter, any other officer to whom such matter is referred
because of such officer's knowledge of and familiarity with the particular
subject.

         Rounding Account: The separate trust account maintained with the
Trustee pursuant to Section 3.22, which account shall bear a designation clearly
indicating that the funds deposited therein are held in trust for the benefit of
the Trust on behalf of the Class A-3 Certificateholders, or any other account
serving a similar function acceptable to the Rating Agencies, and which account
provides that the Trustee may make, or cause to be made, withdrawals as provided
in Section 3.22 hereof, to the extent of the amount then remaining in the
Rounding Account.

         Rounding Amount: For each Distribution Date, the amount of funds, if
any, needed to be withdrawn from the Rounding Account and used to round the
amount of any distributions in reduction of the Class A-3 Principal Balance on
such Distribution Date upward to the next higher integral multiple of $1,000.

         S&P: Standard & Poor's Ratings Services, a division of The McGraw-Hill
Companies, Inc., provided that at any time it be a Rating Agency.

         Scheduled Payment: With respect to any Distribution Date (other than
the Last Scheduled Distribution Date) and the Class A-3-L Regular Interest, the
sum of (i) the Interest Distribution Amount for such Distribution Date for such
Class of Regular Interests and (ii) the principal portion of any Allocated
Realized Losses allocated to the Class A-3-L Regular Interest on such
Distribution Date. With respect to the Last Scheduled Distribution Date and the
Class A-3-L Regular Interest, the sum of (i) the Class Principal Balance of the
Class A-3-L Regular Interest, (ii) the Interest Distribution Amount for such
Distribution Date for such Class of Regular Interests and (iii) the principal
portion of any Allocated Realized Losses allocated to the Class A-3-L Regular
Interest on such Distribution Date (after giving effect to all other
distributions to be made thereon on such Distribution Date). With respect any
Distribution Date after the first date on which (x) the Class Principal Balance
of the Underlying Certificates is less than or equal to 10% of the Class
Principal Balance of the Underlying Certificates as of the Closing Date and the
Certificate Administrator exercises its option to terminate this Agreement
pursuant to Section 9.01 hereof or (y) the aggregate Principal Balance of the
Mortgage Loans is less than or equal to 5% of the aggregate Principal Balance of
the Mortgage Loans as of the Cut-Off Date and the Master Servicer exercises its
option to terminate the Pooling and Servicing Agreement pursuant to Section 9.01
thereof, the sum of (i) the Class Principal Balance of the Class A-3-L Regular
Interest (after giving effect to all other distributions to be made thereon on
such Distribution Date), (ii) the Interest Distribution Amount for such
Distribution Date for such Class of Regular Interests and (iii) the principal
portion of any Allocated Realized Losses allocated to the Class A-3-L Regular
Interest on such Distribution Date (without duplication to any amounts
distributed pursuant to the first sentence of this definition of "Scheduled
Payment").

         Secretary of State: The Secretary of State of the State of Delaware.

         Securities Act: The Securities Act of 1933, as amended.

         Special Retail Certificates: The Class A-3 Certificates.

                                       30
<PAGE>

         Statutory Trust Statute: Chapter 38 of Title 12 of the Delaware Code,
12 Del.C.ss.3801 et seq., as the same may be amended from time to time.

         Step Down Percentage: For any Distribution Date, the percentage
indicated below:

          Distribution Date Occurring In             Step Down Percentage
          --------------------------------           --------------------
          March 2004 through February 2009                     0%
          March 2009 through February 2010                     30%
          March 2010 through February 2011                     40%
          March 2011 through February 2012                     60%
          March 2012 through February 2013                     80%
          March 2013 and after                                100%


         Tax Matters Person: With respect to each of REMIC I and REMIC II, a
Holder of a Class R Certificate with a Percentage Interest of at least 0.01% or
any Permitted Transferee of such Class R Certificateholder designated as
succeeding to the position of Tax Matters Person in a notice to the Trustee
signed by authorized representatives of the transferor and transferee of such
Class R Certificate. The Company is hereby appointed to act as the Tax Matters
Person for REMIC I and REMIC II so long as it holds a Class R Certificate with a
Percentage Interest of at least 0.01%. The Company is hereby appointed to act as
agent for the Tax Matters Person for REMIC I and REMIC II, to perform the
functions of such Tax Matters Person as provided herein, so long as the Company
is the Certificate Administrator hereunder, in the event that the Company ceases
to hold a Class R Certificate with the required Percentage Interest. In the
event that the Company ceases to be the Certificate Administrator hereunder, the
successor Certificate Administrator is hereby appointed to act as agent for the
Tax Matters Person for REMIC I and REMIC II, to perform the functions of such
Tax Matters Person as provided herein. If the Tax Matters Person for REMIC I and
REMIC II becomes a Disqualified Organization, the last preceding Holder, that is
not a Disqualified Organization, of the Class R Certificate held by the
Disqualified Organization shall be Tax Matters Person pursuant to and as
permitted by Section 5.01(c). If any Person is appointed as tax matters person
by the Internal Revenue Service pursuant to the Code, such Person shall be Tax
Matters Person.

         Termination Date: The date upon which final payment of the Certificates
will be made pursuant to the procedures set forth in Section 9.01(b).

         Termination Payment: The final payment delivered to the
Certificateholders on the Termination Date pursuant to the procedures set forth
in Section 9.01(b).

         Transfer: Any direct or indirect transfer or sale of any Ownership
Interest in a Residual Certificate.

         Transferee: Any Person who is acquiring by Transfer any Ownership
Interest in a Residual Certificate.



                                       31
<PAGE>

         Transferee Affidavit and Agreement: An affidavit and agreement in the
form attached hereto as Exhibit J.

         Trust: WaMu Mortgage Pass-Through Certificates Series 2004-RS1 Trust, a
Delaware statutory trust, created pursuant to this Agreement.

         Trust Assets: The following assets: (i) the Underlying Certificates and
all rights pertaining thereto; (ii) such assets as from time to time may be held
by the Trust (or its duly appointed agent) in the Certificate Account (except
amounts representing the Certificate Administrator Fee), the Class A-3 Reserve
Fund or the Rounding Account; and (iii) the Certificate Insurance Policy.

         Trustee: Citibank, N.A., or its successor-in-interest as provided in
Section 8.09, or any successor trustee appointed as herein provided.

         Underlying Certificates: The WaMu Mortgage Pass-Through Certificates,
Series 2003-S11 Certificates, Class 2-A-1, issued by the Underlying Trust
pursuant to the Pooling and Servicing Agreement.

         Underlying Trust: WaMu Mortgage Pass-Through Certificates Series
2003-S11 Trust, a Delaware statutory trust, created pursuant to the Pooling and
Servicing Agreement.

         Underwriter:  Deutsche Bank Securities Inc.

         U.S. Person: A citizen or resident of the United States, a corporation,
partnership or other entity created or organized in or under the laws of the
United States, any state thereof or the District of Columbia, or an estate or
trust that is subject to U.S. federal income tax regardless of the source of its
income.

                                   ARTICLE II

        Creation of the Trust; Conveyance of the Trust Assets and REMIC I
               Regular Interests; REMIC Election and Designations;
                       Original Issuance of Certificates

Section 2.01. Creation of the Trust. The Trust is hereby created and shall be
known as "WaMu Mortgage Pass-Through Certificates Series 2004-RS1 Trust". The
purpose of the Trust is, and the Trust shall have the power and authority, to
engage in the following activities, all as provided by and subject to the terms
of this Agreement:

         (i) to acquire, hold, lease, manage, administer, control, invest,
reinvest, operate and/or transfer the Trust Assets and the REMIC II Assets;

         (ii) to issue the REMIC I Regular Interests, the Class R Residual
Interests and the Certificates;

         (iii) to make distributions to the REMIC I Regular Interests and the
Certificates; and

                                       32
<PAGE>

         (iv) to engage in such other activities, including entering into
agreements, as are described in or required by the terms of this Agreement or as
are necessary, suitable or convenient to accomplish the foregoing or incidental
thereto.

Citibank, N.A. is hereby appointed as a trustee of the Trust, to have all the
rights, duties and obligations of the Trustee with respect to the Trust
expressly set forth hereunder, and Citibank, N.A. hereby accepts such
appointment and the Trust created hereby. Christiana Bank & Trust Company is
hereby appointed as a Delaware trustee of the Trust, to have all the rights,
duties and obligations of the Delaware Trustee with respect to the Trust
hereunder, and Christiana Bank & Trust Company hereby accepts such appointment
and the Trust created hereby. It is the intention of the Company, the Trustee
and the Delaware Trustee that the Trust constitute a statutory trust under the
Statutory Trust Statute, that this Agreement constitute the governing instrument
of the Trust, and that this Agreement amend and restate the Original Trust
Agreement. The parties hereto acknowledge and agree that, prior to the execution
and delivery hereof, the Delaware Trustee has filed the Certificate of Trust.

         The assets of the Trust shall remain in the custody of the Trustee, on
behalf of the Trust, and shall be owned by the Trust except as otherwise
expressly set forth herein. Moneys to the credit of the Trust shall be held by
the Trustee and invested as provided herein. All assets received and held in the
Trust will not be subject to any right, charge, security interest, lien or claim
of any kind in favor of either of Citibank, N.A. or Christiana Bank & Trust
Company in its own right, or any Person claiming through it. Neither the Trustee
nor the Delaware Trustee, on behalf of the Trust, shall have the power or
authority to transfer, assign, hypothecate, pledge or otherwise dispose of any
of the assets of the Trust to any Person, except as permitted herein. No
creditor of a beneficiary of the Trust, of the Trustee, of the Delaware Trustee,
of the Certificate Administrator or of the Company shall have any right to
obtain possession of, or otherwise exercise legal or equitable remedies with
respect to, the property of the Trust, except in accordance with the terms of
this Agreement.

Section 2.02. Restrictions on Activities of the Trust. Notwithstanding any other
provision of this Agreement and any provision of law that otherwise so empowers
the Trust, so long as any Certificates are outstanding, the Trust shall not, and
none of the Trustee, the Delaware Trustee, the Company or the Certificate
Administrator shall knowingly cause the Trust to, do any of the following:

         (i) engage in any business or activity other than those set forth in
Section 2.01;

         (ii) incur or assume any indebtedness except for such indebtedness that
may be incurred by the Trust in connection with the execution or performance of
this Agreement or any other agreement contemplated hereby;

         (iii) guarantee or otherwise assume liability for the debts of any
other party;

         (iv) do any act in contravention of this Agreement or any other
agreement contemplated hereby to which the Trust is a party;

         (v) do any act which would make it impossible to carry on the ordinary
business of the Trust;

         (vi) confess a judgment against the Trust;

         (vii) possess or assign the assets of the Trust for other than a Trust
purpose;

         (viii) cause the Trust to lend any funds to any entity, except as
contemplated by this Agreement; or

         (ix) change the purposes and powers of the Trust from those set forth
in this Agreement.

Section 2.03. Separateness Requirements. Notwithstanding any other provision of
this Agreement and any provision of law that otherwise so empowers the Trust, so
long as any Certificates are outstanding, the Trust shall perform the following:

         (i) except as expressly permitted by this Agreement, maintain its
books, records, bank accounts and files separate from those of any other Person;

         (ii) except as expressly permitted by this Agreement, maintain its
assets in its own separate name and in such a manner that it is not costly or
difficult to segregate, identify, or ascertain such assets;

         (iii) consider the interests of the Trust's creditors in connection
with its actions;

         (iv) hold itself out to creditors and the public as a legal entity
separate and distinct from any other Person and correct any known
misunderstanding regarding its separate identity and refrain from engaging in
any activity that compromises the separate legal identity of the Trust;

         (v) prepare and maintain separate records, accounts and financial
statements in accordance with generally accepted accounting principles,
consistently applied, and susceptible to audit. To the extent it is included in
consolidated financial statements or consolidated tax returns, such financial
statements and tax returns will reflect the separateness of the respective
entities and indicate that the assets of the Trust will not be available to
satisfy the debts of any other Person;



                                       33
<PAGE>

         (vi) allocate and charge fairly and reasonably any overhead shared with
any other Person;

         (vii) transact all business with affiliates on an arm's-length basis
and pursuant to written, enforceable agreements;

         (viii) conduct business solely in the name of the Trust. In that regard
all written and oral communications of the Trust, including, without limitation,
letters, invoices, purchase orders and contracts, shall be made solely in the
name of the Trust;

         (ix) maintain a separate office through which its business shall be
conducted, provided that such office may be an office of the Trustee, which
office shall not be shared with the Company or any affiliates of the Company;

                                       34
<PAGE>

         (x) in the event that services have been or are in the future performed
or paid by any Person on behalf of the Trust (other than the Trustee, the
Delaware Trustee, the Certificate Administrator or the Tax Matters Person as
permitted herein), reimburse such Person, as applicable, for the commercially
reasonable value of such services or expenses provided or incurred by such
Person. Accordingly, (i) the Trust shall reimburse such Person, as applicable,
for the commercially reasonable value of such services or expenses provided or
incurred by such Person; (ii) to the extent invoices for such services are not
allocated and separately billed to the Trust, the amount thereof that was or is
to be allocated and separately billed to the Trust was or will be reasonably
related to the services provided to the Trust; and (iii) any other allocation of
direct, indirect or overhead expenses for items shared between the Trust and any
other Person, was or will be, to the extent practicable, allocated on the basis
of actual use or value of services rendered or otherwise on a basis reasonably
related to actual use or the value of services rendered;

         (xi) except as expressly permitted by this Agreement, not commingle its
assets or funds with those of any other Person;

         (xii) except as expressly permitted by this Agreement, not assume,
guarantee, or pay the debts or obligations of any other Person;

         (xiii) except as expressly permitted by this Agreement, not pledge its
assets for the benefit of any other Person;

         (xiv) not hold out its credit or assets as being available to satisfy
the obligations of others;

         (xv) pay its liabilities only out of its funds;

         (xvi) pay the salaries of its own employees, if any; and

         (xvii) cause the agents and other representatives of the Trust, if any,
to act at all times with respect to the Trust consistently and in furtherance of
the foregoing.

         None of the Trustee, the Delaware Trustee, the Company or the
Certificate Administrator shall take any action that is inconsistent with the
purposes of the Trust or Section 2.02 or Section 2.03. Neither the Company nor
the Certificate Administrator shall direct the Trustee or the Delaware Trustee
to take any action that is inconsistent with the purposes of the Trust or
Section 2.02 or Section 2.03.

Section 2.04.     Conveyance of Trust Assets; Security Interest.

         Concurrently with the execution and delivery hereof, the Company does
hereby irrevocably sell, transfer, assign, set over and otherwise convey to the
Trust, without recourse, all the Company's right, title and interest in and to
the Underlying Certificates, including but not limited to all scheduled payments
of principal and interest due on the Underlying Certificates after the Closing


                                       35
<PAGE>

Date (such transfer and assignment by the Company to be referred to herein as
the "Conveyance," and the assets so transferred and assigned to be referred to
herein as the "Conveyed Assets"). The Company shall cause the Underwriter to
cause DTC to transfer the Underlying Certificates directly to the Trustee.

         It is the express intent of the parties hereto that the Conveyance of
the Conveyed Assets to the Trust by the Company as provided in this Section 2.04
be, and be construed as, an absolute sale of the Conveyed Assets. It is,
further, not the intention of the parties that such Conveyance be deemed the
grant of a security interest in the Conveyed Assets by the Company to the Trust
to secure a debt or other obligation of the Company. However, in the event that,
notwithstanding the intent of the parties, the Conveyed Assets are held to be
the property of the Company, or if for any other reason this Agreement is held
or deemed to create a security interest in the Conveyed Assets, then

         (a) this Agreement shall be deemed to be a security agreement;

         (b) the Conveyance provided for in this Section 2.04 shall be deemed to
be a grant by the Company to the Trust of, and the Company hereby grants to the
Trust, to secure all of the Company's obligations hereunder, a security interest
in all of the Company's right, title, and interest, whether now owned or
hereafter acquired, in and to:

         (I) (i) the Underlying Certificates and all distributions with respect
thereto payable on and after the Closing Date; (ii) the Certificate Account, the
Class A-3 Reserve Fund, the Rounding Account and all money or other property
held therein; and (iii) the Certificate Insurance Policy;

         (II) All rights arising from or by virtue of the disposition of, or
collections with respect to, or insurance proceeds payable with respect to, or
claims against other persons with respect to, all or any part of the collateral
described in (I) above (including any accrued discount realized on liquidation
of any investment purchased at a discount);

         (III) All accounts, general intangibles, chattel paper, instruments,
documents, money, deposit accounts, goods, letters of credit, letter-of-credit
rights, oil, gas, and other minerals, and investment property consisting of,
arising from or relating to any of the foregoing; and

         (IV) All proceeds of the foregoing;

         (c) the possession by the Trust of any of the foregoing property shall
be deemed to be possession by the secured party or possession by a purchaser for
purposes of perfecting the security interest pursuant to the Uniform Commercial
Code (including, without limitation, Sections 9-313 and 9-314 thereof) as in
force in the relevant jurisdiction; and

         (d) notifications to persons holding such property, and
acknowledgments, receipts or confirmations from persons holding such property,
shall be deemed to be notifications to, or acknowledgments, receipts or
confirmations from, securities intermediaries, bailees or agents of, or persons
holding for, the Trust, as applicable, for the purpose of perfecting such
security interest under applicable law.



                                       36
<PAGE>

         The Company shall file such financing statements, and the Company and
the Trustee acting on behalf of the Trust at the direction of the Company shall,
to the extent consistent with this Agreement, take such other actions as may be
necessary to ensure that, if this Agreement were deemed to create a security
interest in the Conveyed Assets, such security interest would be deemed to be a
perfected security interest of first priority under applicable law and will be
maintained as such throughout the term of the Agreement. In connection herewith,
the Trust shall have all of the rights and remedies of a secured party and
creditor under the Uniform Commercial Code as in force in the relevant
jurisdiction.

Section 2.05.     [Reserved].

Section 2.06.     REMIC Election for REMIC I.

         The Tax Matters Person, shall, on behalf of REMIC I, elect to treat
REMIC I as a REMIC within the meaning of Section 860D of the Code and, if
necessary, under applicable state laws. Such election shall be included in the
Form 1066 and any appropriate state return to be filed on behalf of REMIC I for
its first taxable year.

         The Closing Date is hereby designated as the "startup day" of REMIC I
within the meaning of Section 860G(a)(9) of the Code.

         The regular interests (as set forth in the table contained in the
Preliminary Statement hereto) relating to REMIC I are hereby designated as
"regular interests" in REMIC I for purposes of Section 860G(a)(1) of the Code.
The Class R-1 Residual Interest is hereby designated as the sole class of
"residual interest" in REMIC I for purposes of Section 860G(a)(2) of the Code.
The REMIC I Regular Interests and the Class R-1 Residual Interest shall together
be deemed to be a separate series of beneficial interests in the assets of the
Trust consisting of the REMIC I Assets pursuant to Section 3806(b)(2) of the
Statutory Trust Statute.

         The parties intend that the affairs of REMIC I shall constitute, and
that the affairs of REMIC I shall be conducted so as to qualify REMIC I as a
REMIC. In furtherance of such intention, the Tax Matters Person shall, on behalf
of REMIC I: (a) prepare and file, or cause to be prepared and filed, a federal
tax return using a calendar year as the taxable year and using an accrual method
of accounting for REMIC I when and as required by the REMIC Provisions and other
applicable federal income tax laws; (b) make an election, on behalf of the
trust, for REMIC I to be treated as a REMIC on the federal tax return of REMIC I
for its first taxable year, in accordance with the REMIC Provisions; (c) prepare
and forward, or cause to be prepared and forwarded, to the Holders of the REMIC
I Regular Interests and the Class R-1 Residual Interest and the Trustee, all
information reports as and when required to be provided to them in accordance
with the REMIC Provisions, and make available the information necessary for the
application of Section 860E(e) of the Code; (d) conduct the affairs of REMIC I
at all times that any REMIC I Regular Interests are outstanding so as to
maintain the status of REMIC I as a REMIC under the REMIC Provisions; (e) not
knowingly or intentionally take any action or omit to take any action that would
cause the termination of the REMIC status of REMIC I; and (f) pay the amount of
any federal prohibited transaction penalty taxes imposed on REMIC I when and as
the same shall be due and payable (but such obligation shall not prevent the
Company or any other appropriate person from contesting any such tax in
appropriate proceedings and shall not prevent the Company from withholding
payment of such tax, if permitted by law, pending the outcome of such


                                       37
<PAGE>

proceedings); provided, that the Company shall be entitled to be indemnified by
REMIC I for any such prohibited transaction penalty taxes if the Company's
failure to exercise reasonable care was not the primary cause of the imposition
of such prohibited transaction penalty taxes.

         The Trustee and the Certificate Administrator shall promptly provide
the Company with such information in the possession of the Trustee or the
Certificate Administrator, respectively, as the Company may from time to time
request for the purpose of enabling the Company to prepare tax returns.

         In the event that any tax is imposed on "prohibited transactions" of
REMIC I as defined in Section 860F of the Code and not paid by the Company
pursuant to clause (f) of the second preceding paragraph, such tax shall be
charged against amounts otherwise distributable to the Class R-1 Residual
Interest. Notwithstanding anything to the contrary contained herein, the Trustee
is hereby authorized to retain from amounts otherwise distributable to the Class
R-1 Residual Interest on any Distribution Date sufficient funds to reimburse the
Tax Matters Person (or any agent therefor appointed in accordance with the
definition of "Tax Matters Person" herein, if applicable), for the payment of
such tax (upon the written request of the Tax Matters Person or its agent, to
the extent reimbursable, and to the extent that the Tax Matters Person or its
agent has not been previously reimbursed therefor).

Section 2.07.     [Reserved].

Section 2.08. Representations and Warranties of the Company. The Company hereby
represents and warrants to the Trust that immediately prior to the conveyance of
the Underlying Certificates pursuant to Section 2.04 herein, the Company had
good title to, and was the sole owner of, the Underlying Certificates free and
clear of any pledge, lien, encumbrance or security interest and such conveyance
validly transfers ownership of the Underlying Certificate to the Trustee free
and clear of any pledge, lien, encumbrance or security interest.

Section 2.09. Acknowledgment of Transfer of Trust Assets. The Trustee hereby
acknowledges and accepts on behalf of the Trust the transfer and assignment to
the Trust of the Trust Assets, and declares that as of the Closing Date it holds
and shall hold any documents constituting a part of the Trust Assets, and the
Trust Assets, as Trustee in trust, upon the trust herein set forth, for the use
and benefit of all present and future Holders of the REMIC I Regular Interests
and the Class R-1 Residual Interest. In connection therewith, as of the Closing
Date, in exchange for the Trust Assets, the Trustee on behalf of the Trust does
hereby issue to the Company the REMIC I Regular Interests and the Class R-1
Residual Interest.

Section 2.10. Conveyance of REMIC I Regular Interests; Security Interest.
Concurrently with the execution and delivery hereof, the Company does hereby
irrevocably sell, transfer, assign, set over, and otherwise convey to the Trust,
without recourse, all the Company's right, title and interest in and to the
REMIC II Assets, including all interest and principal received by the Company on
or with respect to the REMIC I Regular Interests after the Closing Date.


                                       38
<PAGE>

Pursuant to Section 3818 of the Statutory Trust Statute, the REMIC I Regular
Interests shall not be cancelled and shall be held as treasury interests owned
by the Trust. It is the express intent of the parties hereto that the conveyance
of the REMIC II Assets to the Trust by the Company as provided in this Section
2.10 be, and be construed as, an absolute sale of the REMIC II Assets. It is,
further, not the intention of the parties that such conveyance be deemed the
grant of a security interest in the REMIC II Assets by the Company to the Trust
to secure a debt or other obligation of the Company. However, in the event that,
notwithstanding the intent of the parties, the REMIC II Assets are held to be
the property of the Company, or if for any other reason this Agreement is held
or deemed to create a security interest in the REMIC II Assets, then

         (a) this Agreement shall be deemed to be a security agreement;

         (b) the conveyance provided for in this Section 2.10 shall be deemed to
be a grant by the Company to the Trust of, and the Company hereby grants to the
Trust, to secure all of the Company's obligations hereunder, a security interest
in all of the Company's right, title, and interest, whether now owned or
hereafter acquired, in and to:

         (I) The REMIC I Regular Interests, including without limitation all
rights represented thereby in and to (i) the Underlying Certificates and all
distributions with respect thereto payable on and after the Closing Date, (ii)
the Certificate Account, the Class A-3 Reserve Fund, the Rounding Account and
all money or other property held therein; (iii) the Certificate Insurance
Policy; and (iv) all rights arising from or by virtue of the disposition of, or
collections with respect to, or insurance proceeds payable with respect to, or
claims against other persons with respect to, all or any part of the collateral
described in (i)-(iii) above (including any accrued discount realized on
liquidation of any investment purchased at a discount);

         (II) All accounts, general intangibles, chattel paper, instruments,
documents, money, deposit accounts, goods, letters of credit, letter-of-credit
rights, oil, gas, and other minerals, and investment property consisting of,
arising from or relating to any of the foregoing; and

         (III) All proceeds of the foregoing;

         (c) the possession by the Trust of any of the foregoing property shall
be deemed to be possession by the secured party or possession by a purchaser for
purposes of perfecting the security interest pursuant to the Uniform Commercial
Code (including, without limitation, Sections 9-313 and 9-314 thereof) as in
force in the relevant jurisdiction; and

         (d) notifications to persons holding such property, and
acknowledgments, receipts or confirmations from persons holding such property,
shall be deemed notifications to, or acknowledgments, receipts or confirmations
from, securities intermediaries, bailees or agents of, or persons holding for,
the Trust, as applicable, for the purpose of perfecting such security interest
under applicable law.

         The Company shall file such financing statements, and the Company and
the Trustee acting on behalf of the Trust at the direction of the Company shall,
to the extent consistent with this Agreement, take such other actions as may be
necessary to ensure that, if this Agreement were deemed to create a security
interest in the REMIC II Assets, such security interest would be deemed to be a
perfected security interest of first priority under applicable law and will be
maintained as such throughout the term of this Agreement. In connection


                                       39
<PAGE>

herewith, the Trust shall have all of the rights and remedies of a secured party
and creditor under the Uniform Commercial Code as in force in the relevant
jurisdiction.

Section 2.11.     REMIC Election for REMIC II.

         The Tax Matters Person shall, on behalf of REMIC II, elect to treat
REMIC II as a REMIC within the meaning of Section 860D of the Code and, if
necessary, under applicable state laws. Such election shall be included in the
Form 1066 and any appropriate state return to be filed on behalf of REMIC II for
its first taxable year.

         The Closing Date is hereby designated as the "startup day" of REMIC II
within the meaning of Section 860G(a)(9) of the Code.

         The regular interests (as set forth in the table contained in the
Preliminary Statement hereto) relating to REMIC II are hereby designated as
"regular interests" in REMIC II for purposes of Section 860G(a)(1) of the Code.
The Class R-2 Residual Interest is hereby designated as the sole class of
"residual interest" in REMIC II for purposes of Section 860G(a)(2) of the Code.
The REMIC II Regular Interests and the Class R-2 Residual Interest shall
together be deemed to be a separate series of beneficial interests in the assets
of the Trust consisting of the REMIC II Assets pursuant to Section 3806(b)(2) of
the Statutory Trust Statute.

         The parties intend that the affairs of REMIC II shall constitute, and
that the affairs of REMIC II shall be conducted so as to qualify it as, a REMIC.
In furtherance of such intention, the Tax Matters Person shall, on behalf of
REMIC II: (a) prepare and file, or cause to be prepared and filed, a federal tax
return using a calendar year as the taxable year for REMIC II when and as
required by the REMIC provisions and other applicable federal income tax laws;
(b) make an election, on behalf of REMIC II, to be treated as a REMIC on the
federal tax return of REMIC II for its first taxable year, in accordance with
the REMIC provisions; (c) prepare and forward, or cause to be prepared and
forwarded, to the Certificateholders and the Holders of the Class R-2 Residual
Interest all information reports as and when required to be provided to them in
accordance with the REMIC provisions; (d) conduct the affairs of REMIC II at all
times that any of the Certificates are outstanding so as to maintain the status
of REMIC II as a REMIC under the REMIC provisions; (e) not knowingly or
intentionally take any action or omit to take any action that would cause the
termination of the REMIC status of REMIC II; and (f) pay the amount of any
federal prohibited transaction penalty taxes imposed on REMIC II when and as the
same shall be due and payable (but such obligation shall not prevent the Company
or any other appropriate person from contesting any such tax in appropriate
proceedings and shall not prevent the Company from withholding payment of such
tax, if permitted by law, pending the outcome of such proceedings); provided,
that the Company shall be entitled to be indemnified from REMIC II for any such
prohibited transaction penalty taxes if the Company's failure to exercise
reasonable care was not the primary cause of the imposition of such prohibited
transaction penalty taxes.

         In the event that any tax is imposed on "prohibited transactions" of
REMIC II as defined in Section 860F of the Code and not paid by the Company
pursuant to clause (f) of the preceding paragraph, such tax shall be charged


                                       40
<PAGE>

against amounts otherwise distributable to the Holders of the Class R-2 Residual
Interest. Notwithstanding anything to the contrary contained herein, the Company
is hereby authorized to retain from amounts otherwise distributable to the
Holders of the Class R-2 Residual Interest on any Distribution Date sufficient
funds to reimburse the Company for the payment of such tax (to the extent that
the Company has not been previously reimbursed therefor).

Section 2.12. Acknowledgement of Transfer of REMIC II Assets; Authentication of
Certificates. The Trustee hereby acknowledges and accepts on behalf of the Trust
the assignment to the Trust of the REMIC II Assets and declares that as of the
Closing Date it holds and shall hold any documents constituting a part of the
REMIC II Assets, and the REMIC II Assets, as Trustee in trust, upon the trust
herein set forth, for the use and benefit of all present and future Holders of
the Certificates (other than the Class R Certificates) and the Class R-2
Residual Interest. In connection therewith, as of the Closing Date, in exchange
for the REMIC II Assets, the Trustee on behalf of the Trust shall cause to be
authenticated and delivered, upon and pursuant to the order of the Company, the
Certificates in Authorized Denominations.

Section 2.13. Legal Title. Legal title to all assets of the Trust shall be
vested at all times in the Trust as a separate legal entity.

Section 2.14. Compliance with ERISA Requirements. For purposes of ensuring
compliance with the requirements of the "underwriter's exemption" (U.S.
Department of Labor Prohibited Transaction Exemption 2002-41, 67 Fed. Reg. 54487
(Aug. 22, 2002)), issued under ERISA, and for the avoidance of any doubt as to
the applicability of other provisions of this Agreement, to the extent permitted
by applicable law and except as contemplated by this Agreement, (1) the Trust
shall not be a party to any merger, consolidation or reorganization, or
liquidate or sell its assets and (2) so long as any Certificates are
outstanding, none of the Company, the Trustee or the Delaware Trustee shall
institute against the Trust, or join in any institution against the Trust of,
any bankruptcy or insolvency proceedings under any federal or state bankruptcy,
insolvency or similar law.

                                  ARTICLE III

                  Administration of the Underlying Certificates

Section 3.01. The Company to Act as Certificate Administrator. The Company shall
act as Certificate Administrator on behalf of the Trust and for the benefit of
the Certificateholders in accordance with the terms hereof. The Certificate
Administrator shall make reasonable efforts to collect or cause to be collected
all payments called for under the terms and provisions of the Underlying
Certificates. The Certificate Administrator hereby undertakes to collect and
remit to the Trustee for deposit in the Certificate Account all amounts due with
respect to the Underlying Certificates, to the extent not remitted directly to
the Trustee under the Pooling and Servicing Agreement. The Certificate
Administrator may perform its administrative responsibilities through agents or
independent contractors, but shall not thereby be released from any of its
responsibilities hereunder and the Certificate Administrator shall diligently
pursue all of its rights against such agents or independent contractors.



                                       41
<PAGE>

Section 3.02.     [Reserved].

Section 3.03.     [Reserved].

Section 3.04. The Certificate Account. On or prior to the Closing Date, the
Trustee shall establish the Certificate Account, which shall be entitled
"Washington Mutual Mortgage Securities Corp. Certificate Account under the
Amended and Restated Trust Agreement, dated as of February 26, 2004, among
Washington Mutual Mortgage Securities Corp., as Depositor and Certificate
Administrator, Citibank, N.A., as the Trustee, and Christiana Bank & Trust
Company, as the Delaware Trustee, for the benefit of WaMu Mortgage Pass-Through
Certificates Series 2004-RS1 Trust created pursuant thereto". Promptly after the
Closing Date, the Trustee shall communicate to the Certificate Administrator the
account number and wiring instructions for the Certificate Account. The Trustee
shall deposit or cause to be deposited in the Certificate Account, upon receipt,
all payments and other collections received on or in respect of the Underlying
Certificates subsequent to the Closing Date. In addition, the Certificate
Administrator shall deposit into the Certificate Account any amounts paid by the
Certificate Administrator in connection with the exercise of its option to
terminate this Agreement pursuant to Section 9.01. The Trustee shall deposit
into the Certificate Account amounts received under the Certificate Insurance
Policy in accordance with Section 3.21(b) hereof.

Section 3.05.     [Reserved].

Section 3.06.     [Reserved].

Section 3.07.     [Reserved].

Section 3.08.     [Reserved].

Section 3.09. Compliance with Federal Withholding Requirements. Notwithstanding
any other provision of this Agreement, the Certificate Administrator and the
Trustee, as applicable, shall comply with all federal withholding requirements
with respect to payments to Certificateholders of interest or original issue
discount that the Certificate Administrator or the Trustee reasonably believes
are applicable under the Code. The consent of Certificateholders shall not be
required for any such withholding. Without limiting the foregoing, the
Certificate Administrator agrees that it will not withhold with respect to
payments of interest or original issue discount in the case of a
Certificateholder that has furnished or caused to be furnished an effective Form
W-8 or an acceptable substitute form or a successor form and who is not a "10
percent shareholder" within the meaning of Code Section 871(h)(3)(B) or a
"controlled foreign corporation" described in Code Section 881(c)(3)(C) with
respect to REMIC I or REMIC II or the depositor. In the event the Trustee
withholds any amount from interest or original issue discount payments or
advances thereof to any Certificateholder pursuant to federal withholding
requirements, the Trustee shall indicate the amount withheld to such
Certificateholder.

Section 3.10.     [Reserved].

Section 3.11. Compensation to the Certificate Administrator. As compensation for
its activities hereunder, the Certificate Administrator shall be entitled to
receive the Certificate Administrator Fee pursuant to Section 4.04. The


                                       42
<PAGE>

Certificate Administrator shall be required to pay all expenses incurred by it
in connection with its activities hereunder and shall not be entitled to
reimbursement therefor, except as specifically provided herein.

Section 3.12. Reports to the Trustee; Certificate Account Statement. Not later
than 15 days after each Distribution Date, the Certificate Administrator shall
forward a statement, certified by an Administrative Officer, to the Trustee and
the Certificate Insurer setting forth the status of the Certificate Account as
of the close of business on such Distribution Date and showing, for the period
covered by such statement, the aggregate of deposits into and withdrawals from
the Certificate Account for each category of deposit specified in Section 3.04
and each category of withdrawal specified in Section 3.05, and stating that all
distributions required by this Agreement have been made (or if any required
distribution has not been made, specifying the nature and amount thereof). The
Trustee shall make available such statements to any Certificateholder upon
request at the expense of the Certificate Administrator.

Section 3.13. Annual Statement as to Compliance. The Certificate Administrator
shall deliver to the Trustee and the Certificate Insurer, on or before April 30
of each year, beginning with the first April 30 succeeding the Cut-Off Date by
at least six months, an Officer's Certificate stating as to the signer thereof,
that (i) a review of the activities of the Certificate Administrator during the
preceding calendar year and performance under this Agreement has been made under
such officer's supervision, and (ii) to the best of such officer's knowledge,
based on such review, the Certificate Administrator has fulfilled all its
obligations under this Agreement throughout such year, or, if there has been a
default in the fulfillment of any such obligation, specifying each such default
known to such officer and the nature and status thereof. Copies of such
statement shall be provided by the Certificate Administrator to
Certificateholders upon request or by the Trustee (solely to the extent that
such copies are available to the Trustee) at the expense of the Certificate
Administrator, should the Certificate Administrator fail to so provide such
copies.

Section 3.14.     [Reserved].

Section 3.15. Annual Independent Public Accountants' Servicing Report. On or
before April 30 of each year, beginning with the first April 30 succeeding the
Cut-Off Date by at least six months, the Certificate Administrator, at its
expense, shall cause a firm of independent public accountants to furnish a
statement to the Trustee and the Certificate Insurer to the effect that, in
connection with the firm's examination of the financial statements as of the
previous December 31 of the Certificate Administrator's parent corporation
(which shall include a limited examination of the Certificate Administrator's
financial statements), nothing came to their attention that indicated that the
Certificate Administrator was not in compliance with Section 3.02, Section 3.03,
Section 3.04, Section 3.05, Section 3.11, Section 3.12 and Section 3.13 of this
Agreement, except for (i) such exceptions as such firm believes to be
immaterial, and (ii) such other exceptions as are set forth in such statement.

Section 3.16. Maintenance of the Class A-3 Reserve Fund. On or prior to the
Closing Date, the Certificate Administrator shall cause to be established and
maintained the Class A-3 Reserve Fund, into which an amount equal to $15,000
shall be contributed by the Underwriter, to provide coverage with respect to any
Class A-3 Covered Shortfall Amount. For each Distribution Date, so long as funds


                                       43
<PAGE>

remain on deposit in the Class A-3 Reserve Fund, the Certificate Administrator
shall calculate the Class A-3 Covered Shortfall Amount for such Distribution
Date, and shall notify the Trustee by noon New York City time two Business Days
prior to the Distribution Date of such aggregate amount. On each such
Distribution Date, the Trustee shall then withdraw from the Class A-3 Reserve
Fund, to the extent funds are available therein, the Class A-3 Covered Shortfall
Amount and deposit such amount in the Certificate Account for payment to the
Class A-3 Certificateholders pursuant to Section 4.04(a) (and shall be deemed to
have distributed such amount to the Class A-3-L Regular Interest pursuant to
Section 4.01).

         The Trustee shall withdraw from the Class A-3 Reserve Fund and pay to
the Underwriter any amounts remaining in the Class A-3 Reserve Fund on the
Distribution Date on which the Class A-3 Principal Balance has been reduced to
zero.

         Amounts on deposit in the Class A-3 Reserve Fund shall not be invested
and shall not be held in an interest-bearing account.

         To the extent that it constitutes a "reserve fund" for purposes of the
REMIC Provisions, the Class A-3 Reserve Fund established hereunder shall be an
"outside reserve fund" as defined in Treasury Regulation 1.860G-2(h), and in
that regard (i) such fund shall be an outside reserve fund and not an asset of
any REMIC, (ii) such fund shall be owned for federal tax purposes by the
Underwriter, and the Underwriter shall report all amounts of income, deduction,
gain or loss accruing therefrom, and (iii) amounts transferred by the REMIC to
the fund shall be treated as distributed by the REMIC to the Underwriter.

Section 3.17.     [Reserved.]

Section 3.18.     [Reserved.]

Section 3.19.     [Reserved.]

Section 3.20.     [Reserved.]

Section 3.21.     Maintenance of the Certificate Insurance Policy; Collections
Thereunder.

         (a) Prior to noon New York City time on the third Business Day prior to
each Distribution Date, the Certificate Administrator shall, with respect to the
Insured Certificates, determine if a Deficiency Amount for such Distribution
Date exists and, if so, shall immediately notify the Trustee in writing of such
amount; the Trustee, upon receipt of such notice, shall complete the Notice and
submit such Notice in accordance with the Certificate Insurance Policy to the
Certificate Insurer no later than 10:00 a.m, New York City time, on the second
Business Day immediately preceding such Distribution Date, as a claim for an
Insured Payment in an amount equal to such Deficiency Amount. If at any time the
Trustee receives a certified copy of an order of an appropriate court that any
payment of principal and interest on the Insured Certificates constitutes a
Avoided Payment, the Trustee, at the expense of the Trust, shall take the
actions required on its part by the terms of the Certificate Insurance Policy to
obtain payment of such Avoided Payment by the Certificate Insurer.

                                       44
<PAGE>

         (b) Upon receipt of an Insured Payment from the Certificate Insurer on
behalf of the Holders of the Insured Certificates, the Trustee shall deposit
such Insured Payment in the Certificate Account. All such amounts on deposit in
the Certificate Account shall remain uninvested. The Trustee shall include on
each Distribution Date any amounts received by it from or on behalf of the
Certificate Insurer with respect to a Deficiency Amount for such Distribution
Date (i) in the amount distributed to the Holders of the Insured Certificates
pursuant to Section 4.04 and (ii) in the amount deemed to have been distributed
to the Class A-3-L Regular Interest and deposited for its benefit into the
Certificate Account pursuant to Section 4.01). If on any Distribution Date the
Trustee or the Certificate Administrator determines (the Certificate
Administrator having notified the Trustee of such determination) that the
Certificate Insurer has paid more under the Certificate Insurance Policy than is
required by the terms thereof, the Trustee shall promptly return the excess
amount to the Certificate Insurer.

         (c) The Trustee shall (i) receive as attorney-in-fact of the Holders of
the Insured Certificates (and each such Holder, by its acceptance of its Insured
Certificates, hereby agrees that the Trustee shall so receive) any Insured
Payment delivered to it by the Certificate Insurer for payment to such Class and
(ii) distribute such Insured Payment to such Holders as set forth in subsection
3.21(b) above. Insured Payments disbursed by the Trustee from proceeds of the
Certificate Insurance Policy shall not be considered payment by the Trust with
respect to the Insured Certificates, nor shall such disbursement of Insured
Payments discharge the obligations of the Trust with respect to the amounts
thereof, and the Certificate Insurer shall become owner of such amounts to the
extent covered by such Insured Payments as the deemed assignee of such Holders.
The Trustee hereby agrees on behalf of the Holders of the Insured Certificates
(and each such Holder, by its acceptance of its Insured Certificates, hereby
agrees) for the benefit of the Certificate Insurer that, to the extent the
Certificate Insurer makes Insured Payments, either directly or indirectly (as by
paying through the Trustee), to the Holder of an Insured Certificate, the
Certificate Insurer will be subrogated to any rights of the Holder of such
Insured Certificate to receive (pursuant to the definition of "REMIC I
Distribution Amount") the amounts for which such Insured Payments were made, to
the extent of such payments, and the Trustee shall pay such amounts to the
Certificate Insurer to the extent included in the REMIC I Distribution Amount
(as notified to the Trustee by the Certificate Administrator in the written
statement required pursuant to Section 4.02).

         (d) On each Distribution Date and prior to making any distributions on
such Distribution Date pursuant to Section 4.04, the Trustee shall withdraw from
the Certificate Account and pay to the Certificate Insurer the Certificate
Insurer Premium as set forth in the statement delivered to the Trustee pursuant
to Section 4.02.

Section 3.22. Maintenance of the Rounding Account; Collections Thereunder. On or
prior to the Closing Date, the Trustee shall establish the Rounding Account, and
the Underwriter shall deposit $999.99 therein. The Certificate Administrator
shall maintain such account to provide, if needed, the applicable Rounding
Amount on any Distribution Date. On the first Distribution Date with respect to
which the Certificate Administrator determines that principal is required to be
distributed to the Special Retail Certificates pursuant to Section 4.04(a)(ii),
and the aggregate amount of such principal is not an amount equal to an integral
multiple of $1,000, the Certificate Administrator shall notify the Trustee by
Noon New York City time two Business Days prior to such Distribution Date of the
applicable Rounding Amount, and the Trustee shall withdraw such Rounding Amount
from the Rounding Account. On each succeeding Distribution Date, prior to the
earlier of (i) the Credit Support Depletion Date and (ii) the date on which any


                                       45
<PAGE>

loss is allocated to the Special Retail Certificates or its Corresponding Class,
with respect to which the Certificate Administrator determines that principal is
required to be distributed to such Class pursuant to Section 4.04(a)(ii), the
aggregate amount of such principal will be applied first to repay to the
Rounding Account any funds withdrawn from the Rounding Account on prior
Distribution Dates which have not been repaid. If the remainder of such
aggregate amount of principal is not an amount equal to an integral multiple of
$1,000, the Certificate Administrator shall notify the Trustee by Noon New York
City time two Business Days prior to such Distribution Date of the applicable
Rounding Amount, and the Trustee shall withdraw from the Rounding Account, to
the extent funds are available therein, the amount so notified by the
Certificate Administrator.

         Any amounts withdrawn by the Trustee from the Rounding Account shall be
deposited in the Certificate Account for distribution to the Holders of the
Special Retail Certificates as described in the immediately preceding paragraph
(and shall be deemed to have been distributed to their Corresponding Class and
deposited for its benefit into the Certificate Account in accordance with
Section 4.01.

         Amounts on deposit in the Rounding Account shall not be invested.

         On the first Distribution Date after the earliest of (i) the Credit
Support Depletion Date, (ii) the date on which any loss is allocated to the
Special Retail Certificates or their Corresponding Class and (iii) the date on
which the Class Principal Balance of the Special Retail Certificates has been
reduced to zero, the Trustee shall remit any amounts then remaining on deposit
in the Rounding Account to the Holders of the Class R-2 Residual Interest.

                                   ARTICLE IV

               Payments to Certificateholders; Payment of Expenses

Section 4.01. Distributions to Certificate Insurer and Holders of REMIC I
Regular Interests and Class R-1 Residual Interest. On each Distribution Date,
the Trustee (or any duly appointed paying agent) (i) shall withdraw from the
Certificate Account the Certificate Insurer Premium payable on such Distribution
Date pursuant to Section 3.21(d) and pay such amount to the Certificate Insurer,
(ii) shall be deemed to have distributed from the Certificate Account (A) the
REMIC I Distribution Amount (other than the Class A-3 Reimbursement Amount) to
the Holders of the REMIC I Regular Interests and (B) the Class A-3 Covered
Shortfall Amount, if any, the Deficiency Amount, if any, and the Rounding
Amount, if any, to the Holders of the Class A-3 Regular Interest, and to have
deposited such amount for their benefit into the Certificate Account, (iii)
shall withdraw from the Certificate Account and distribute to the Certificate
Insurer, in accordance with the written statement received from the Certificate
Administrator pursuant to Section 4.02, any Class A-3 Reimbursement Amount to be
distributed to the Certificate Insurer pursuant to the definition of "REMIC I
Distribution Amount" for such Distribution Date and (iv) from the Certificate
Account shall distribute to the Class R Certificateholders, in accordance with
the written statement received from the Certificate Administrator pursuant to
Section 4.02, the amounts to be distributed to the Holders of the Class R-1
Residual Interest pursuant to the definition of "REMIC I Distribution Amount"
for such Distribution Date. Amounts distributed pursuant to clause (iv) above


                                       46
<PAGE>

shall be distributed by wire transfer in immediately available funds for the
account of each Class R Certificateholder, or by any other means of payment
acceptable to each Class R Certificateholder of record on the immediately
preceding Record Date (other than as provided in Section 9.01 respecting the
final distribution), as specified by each such Certificateholder and at the
address of such Holder appearing in the Certificate Register. Amounts
distributed to the Certificate Insurer pursuant to clause (iii) above shall be
distributed by wire transfer in immediately available funds to such account as
the Certificate Insurer shall designate in writing to the Trustee from time to
time at least one Business Day before any Distribution Date or, at the election
of the Certificate Insurer, by check sent by first class mail to its Notice
Address. Notwithstanding any other provision of this Agreement, no actual
distributions pursuant to clause (ii) of this Section 4.01 shall be made on
account of the deemed distributions described in this paragraph except in the
event of a liquidation of REMIC II and not REMIC I.

Section 4.02. Distribution Reports to the Trustee. Prior to noon New York City
time two Business Days prior to each Distribution Date, the Certificate
Administrator shall provide (x) the Trustee (y) the Certificate Insurer and (z)
the Company (if the Company is no longer acting as Certificate Administrator)
with a statement in writing of (1) the amount, if any, of the Certificate
Insurer Premium, (2) the amounts to be distributed to the Certificate Insurer
pursuant to the definition of "REMIC I Distribution Amount," (3) the Deficiency
Amount, if any, to be paid by the Certificate Insurer, (4) the Class A-3 Covered
Shortfall Amount, if any, to be withdrawn from the Class A-3 Reserve Fund
pursuant to Section 3.16, (5) the Rounding Amount, if any, to be withdrawn from
the Rounding Account pursuant to Section 3.22, (6) the amounts to be applied to
repay any funds withdrawn from the Rounding Account on prior Distribution Dates
pursuant to Section 3.22, (7) the amount, as applicable, of (i) interest, (ii)
the interest portion, if any, of Allocated Realized Losses, (iii) Allocated
Uncompensated Interest Shortfall, (iv) principal, (v) the principal portion of
Allocated Realized Losses and (vi) the Residual Distribution Amount to be
distributed or allocated, as applicable, to each Class of Certificates on such
Distribution Date (such amounts to be determined in accordance with the
definitions of "REMIC I Distribution Amount" and "REMIC II Distribution Amount,"
Section 4.01 and Section 4.04 hereof and other related definitions set forth in
Article I hereof); and (8) the applicable Class Principal Balance after giving
effect to such distributions and allocations.

Section 4.03.     [Reserved.]

Section 4.04.     Distributions to Certificateholders; Payment of Certificate
Administrator Fee.

         (a) On each Distribution Date, the Trustee (or any duly appointed
paying agent) shall (i) withdraw from the Certificate Account the Certificate
Administrator Fee payable on such Distribution Date and pay such amount to the
Certificate Administrator and (ii) withdraw from the Certificate Account (A) the
REMIC II Available Distribution Amount for such Distribution Date and
distribute, from the amount so withdrawn, to the extent of the REMIC II
Available Distribution Amount, the REMIC II Distribution Amount to the
Certificateholders (including the Class R Certificateholders with respect to any
distribution to the Holders of the Class R-2 Residual Interest) (provided that
any portion of such amount distributable to the Special Retail Certificates


                                       47
<PAGE>

shall be used first to pay any amount payable to the Rounding Account pursuant
to Section 3.22) and to the Certificate Insurer in respect of the Certificate
Insurer's subrogation to certain rights to payment due to the Holders of the
Insured Certificates as set forth in Section 3.21, (B) the Class A-3 Covered
Shortfall Amount, if any, deposited therein for distribution on such date
pursuant to Section 3.16 and the Deficiency Amount, if any, and distribute such
amounts to the Holders of the Insured Certificates and (C) the applicable
Rounding Amount, if any, deposited therein for distribution on such date
pursuant to Section 3.22 and distribute the amount so withdrawn to the Special
Retail Certificates in accordance with such Section 3.22, all in accordance with
the written statement received from the Certificate Administrator pursuant to
Section 4.02. Amounts distributed to the Certificateholders pursuant to clause
(ii) above shall be distributed by wire transfer in immediately available funds
for the account of, or by check mailed to, each such Certificateholder of record
on the immediately preceding Record Date (other than as provided in Section 9.01
respecting the final distribution), as specified by each such Certificateholder
and at the address of such Holder appearing in the Certificate Register. Amounts
distributed to the Certificate Insurer pursuant to clause (ii) above shall be
distributed by wire transfer in immediately available funds to such account as
the Certificate Insurer shall designate in writing to the Trustee from time to
time at least one Business Day before any Distribution Date or, at the election
of the Certificate Insurer, by check sent by first class mail to its Notice
Address.

         (b) All reductions in the Certificate Principal Balance of a
Certificate effected by distributions of principal and all allocations of
Allocated Realized Losses made on any Distribution Date shall be binding upon
all Holders of such Certificate and of any Certificate issued upon the
registration of transfer or exchange therefor or in lieu thereof, whether or not
such distribution is noted on such Certificate. The final distribution of
principal of each Certificate (and the final distribution upon the Class R
Certificates upon (i) the termination of REMIC I and REMIC II and (ii) the
payment, or making provision for payment, of all liabilities of the Trust) shall
be payable in the manner provided above only upon presentation and surrender
thereof on or after the Distribution Date therefor at the office or agency of
the Certificate Registrar specified in the notice delivered pursuant to Section
4.04(c)(ii) and Section 9.01(b).

         (c) Whenever the Certificate Administrator has notified the Trustee
that it believes that the entire remaining unpaid Class Principal Balance of any
Class of Certificates will become distributable on the next Distribution Date,
the Trustee shall, no later than the 18th day of the month of such Distribution
Date, mail or cause to be mailed to each Person in whose name a Certificate to
be so retired is registered at the close of business on the Record Date and to
the Rating Agencies (with a copy to the Certificate Insurer) a notice to the
effect that:

         (i) it is expected that funds sufficient to make such final
distribution will be available in the Certificate Account on such Distribution
Date, and

         (ii) if such funds are available, (A) such final distribution will be
payable on such Distribution Date, but only upon presentation and surrender of
such Certificate at the office or agency of the Certificate Registrar maintained
for such purpose (the address of which shall be set forth in such notice), and
(B) no interest shall accrue on such Certificate after such Distribution Date.



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<PAGE>

Section 4.05. Statements to Certificateholders. The Trustee shall make available
the statement required by Section 4.02, and may make available certain other
information, including, without limitation, information required to be provided
by the Trustee pursuant to Sections 3.12 and 3.13, to Certificateholders, the
Certificate Insurer and each Rating Agency through the Trustee's Corporate Trust
home page on the world wide web. Such web page is currently located at
"www.sf.citidirect.com." The location of such web page and the procedures used
therein are subject to change from time to time at the Trustee's discretion.
Certificateholders can also reach the customer service desk by phone at
1-800-422-2066.

         Upon request by any Certificateholder or Rating Agency or the Trustee
or the Certificate Insurer, the Certificate Administrator shall forward to such
Certificateholder or Rating Agency and the Trustee, the Certificate Insurer and
the Company (if the Company is no longer acting as Certificate Administrator) an
additional report which sets forth with respect to the Mortgage Loans:

         (a) The information set forth in Section 4.06(a) through (e) of the
Pooling and Servicing Agreement;

         (b) The amount of the Class A-3 Reimbursement Amount as of the
applicable Determination Date and the amount of any Avoided Payment and any
amount payable to the Certificate Insurer pursuant to its subrogation rights;

         (c) The cumulative amount of Allocated Realized Losses allocated to the
Certificates since the Closing Date; and

         (d) The amount remaining on deposit in the Class A-3 Reserve Fund.

         The Company may make available any reports, statements or other
information to Certificateholders through the Company's home page on the world
wide web. As of the Closing Date, such web page is located at "www.wamumsc.com"
and information is available by clicking on "Investor Information."

Section 4.06. Principal Distributions on the Special Retail Certificates. Prior
to the earlier of (i) the Credit Support Depletion Date and (ii) the date on
which any loss is allocated to the Underlying Certificates by Pro Rata
Allocation, distributions in reduction of the Class Principal Balance of the
Special Retail Certificates will be made in integral multiples of $1,000 at the
request of the appropriate representatives of Deceased Holders of Certificates
of such Class and at the request of Living Holders of Certificates of such Class
or by mandatory distributions, pursuant to Section 4.06(a) and Section 4.06(d).
On and after the earlier of (i) the Credit Support Depletion Date and (ii) the
date on which any loss is allocated to the Underlying Certificates by Pro Rata
Allocation, distributions in reduction of the Class Principal Balance of the
Special Retail Certificates will be made on a pro rata basis pursuant to Section
4.06(e).

         (a) On each Distribution Date (prior to the earlier of (i) the Credit
Support Depletion Date and (ii) the date on which any loss is allocated to the
Underlying Certificates by Pro Rata Allocation) on which principal distributions
to the Special Retail Certificates are made, such distributions will be made in
the following priority:



                                       49
<PAGE>

         (i) first, to requesting Deceased Holders, in the order in which such
requests are received by DTC, but not exceeding an aggregate amount of $100,000
for each requesting Deceased Holder; and

         (ii) second, to requesting Living Holders, in the order in which such
requests are received by DTC, but not exceeding an aggregate amount of $10,000
for each requesting Living Holder.

Thereafter, distributions will be made, with respect to the Special Retail
Certificates, as provided in clauses (i) and (ii) above up to a second $100,000
and $10,000, respectively. This sequence of priorities will be repeated until
all requests for principal distributions by Deceased Holders and Living Holders
of such Class have been honored, to the extent of amounts available for
principal distributions to such Class.

         All requests for principal distributions to Special Retail Certificates
will be accepted in accordance with the provisions set forth in Section 4.06(c).
Requests for principal distributions that are received by the Trustee after the
related Record Date and requests for principal distributions received in a
timely manner but not accepted with respect to any Distribution Date, will be
treated as requests for principal distributions to Special Retail Certificates
on the next succeeding Distribution Date, and each succeeding Distribution Date
thereafter, until each such request is accepted or is withdrawn as provided in
Section 4.06(c). Such requests as are not so withdrawn shall retain their order
of priority without the need for any further action on the part of the
appropriate Holder of the Special Retail Certificate, all in accordance with the
procedures of DTC and the Trustee. Upon the transfer of beneficial ownership of
any Special Retail Certificate, any distribution request previously submitted
with respect to such Certificate will be deemed to have been withdrawn only upon
the receipt by the Trustee on or before the Record Date for such Distribution
Date of notification of such withdrawal in the manner set forth in Section
4.06(c) using a form required by DTC.

         Distributions in reduction of the Class Principal Balance of the
Special Retail Certificates will be applied in an amount equal to the portion of
the REMIC II Available Distribution Amount allocable to such Class pursuant to
Section 4.04, plus any amounts available for distribution from the Rounding
Account established as provided in Section 3.22, provided that the aggregate
distribution of principal to such Class on any Distribution Date shall be made
in an integral multiple of $1,000.

         To the extent that the portion of the Principal Distribution Amount
allocable to the Corresponding Class of the Special Retail Certificates on any
Distribution Date exceeds the aggregate Certificate Principal Balance of Special
Retail Certificates with respect to which principal distribution requests, as
set forth above, have been received, principal distributions in reduction of the
Class Principal Balance of the Special Retail Certificates will be made by
mandatory distribution pursuant to Section 4.06(d).

         (b) A Special Retail Certificate shall be deemed to be held by a
Deceased Holder for purposes of this Section 4.06 if the death of the Holder
thereof is deemed to have occurred. Special Retail Certificates beneficially
owned by tenants by the entirety, joint tenants or tenants in common will be
considered to be beneficially owned by a single owner. The death of a tenant by
the entirety, joint tenant or tenant in common will be deemed to be the death of
the Holder, and the Special Retail Certificates so beneficially owned will be


                                       50
<PAGE>

eligible for priority with respect to principal distributions, subject to the
limitations stated above. Special Retail Certificates beneficially owned by a
trust will be considered to be beneficially owned by each beneficiary of the
trust to the extent of such beneficiary's beneficial interest therein, but in no
event will a trust's beneficiaries collectively be deemed to be Holders of a
number of Special Retail Certificates greater than the number of Special Retail
Certificates of which such trust is the owner. The death of a beneficiary of a
trust will be deemed to be the death of a Holder of the Special Retail
Certificates beneficially owned by the trust to the extent of such beneficiary's
beneficial interest in such trust. The death of an individual who was a tenant
by the entirety, joint tenant or tenant in common in a tenancy which is the
beneficiary of a trust will be deemed to be the death of the beneficiary of such
trust. The death of a person who, during his or her lifetime, was entitled to
substantially all of the beneficial ownership interests in a Special Retail
Certificate will be deemed to be the death of the Holder of such Special Retail
Certificate regardless of the registration of ownership, if such beneficial
ownership interest can be established to the satisfaction of the Trustee. Such
beneficial interest will be deemed to exist in typical cases of street name or
nominee ownership, ownership by a trustee, ownership under the Uniform Gifts to
Minors Act and community property or other joint ownership arrangements between
a husband and wife. Beneficial interest shall include the power to sell,
transfer or otherwise dispose of a Special Retail Certificate and the right to
receive the proceeds therefrom, as well as interest and principal distributions,
as applicable, payable with respect thereto. The Trustee may rely entirely upon
documentation delivered to it in establishing beneficial ownership interests in
Special Retail Certificates. The Trustee shall not be under any duty to
determine independently the occurrence of the death of any deceased Holder. The
Trustee may rely entirely upon documentation delivered to it pursuant to Section
4.06(c) in establishing the eligibility of any Holder to receive the priority
accorded Deceased Holders in Section 4.06(a).

         (c) Requests for principal distributions to any Special Retail
Certificate must be made by delivering a written request therefor to the DTC
Participant or Indirect DTC Participant that maintains the account evidencing
such Holder's interest in such Certificate. In the case of a request on behalf
of a Deceased Holder, appropriate evidence of death and any tax waivers are
required to be forwarded to the Trustee under separate cover. The DTC
Participant should in turn make the request of DTC (or, in the case of an
Indirect DTC Participant, such Indirect DTC Participant must notify the related
DTC Participant of such request, which DTC Participant should make the request
of DTC) on a form required by DTC and provided to the DTC Participant. Upon
receipt of such request, DTC will date and time stamp such request and forward
such request to the Trustee. DTC may establish such procedures as it deems fair
and equitable to establish the order of receipt of requests for such
distributions received by it on the same day. None of the Company, the
Certificate Administrator, the Trust or the Trustee shall be liable for any
delay in delivery of requests for distributions or withdrawals of such requests
by DTC, a DTC Participant or any Indirect DTC Participant.

         The Trustee shall maintain a list of those DTC Participants
representing the appropriate Holders of Special Retail Certificates that have
submitted requests for principal distributions, together with the order of
receipt and the amounts of such requests. Subject to the priorities described in
Section 4.06(a) above, DTC will honor requests for distributions in the order of
their receipt. The Trustee shall notify DTC as to which requests should be
honored on each Distribution Date at least two Business Days prior to such
Distribution Date and shall notify DTC as to the portion of the REMIC II


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<PAGE>

Available Distribution Amount (together with any amounts available for
distribution from the Rounding Account) to be distributed to the Special Retail
Certificates by mandatory distribution pursuant to Section 4.06(d). Requests
shall be honored by DTC in accordance with the procedures, and subject to the
priorities and limitations, described in this Section 4.06. The exact procedures
to be followed by the Trustee and DTC for purposes of determining such
priorities and limitations will be those established from time to time by the
Trustee or DTC, as the case may be. The decisions of the Trustee and DTC
concerning such matters will be final and binding on all affected persons.

         Special Retail Certificates that have been accepted for a distribution
shall be due and payable on the applicable Distribution Date. Such Certificates
shall cease to bear interest after the last calendar day of the month preceding
the month in which such Distribution Date occurs.

         Any Holder of a Special Retail Certificate that has requested a
principal distribution may withdraw its request by so notifying in writing the
DTC Participant or Indirect DTC Participant that maintains such Holder's
account. In the event that such account is maintained by an Indirect DTC
Participant, such Indirect DTC Participant must notify the related DTC
Participant which in turn must forward the withdrawal of such request, on a form
required by DTC, to DTC to be forwarded to the Trustee. If such notice of
withdrawal of a request for distribution has not been received by DTC and
forwarded to the Trustee on or before the Record Date for the next Distribution
Date, the previously made request for a principal distribution will be
irrevocable with respect to the making of principal distributions on such
Distribution Date.

         In the event any requests for principal distributions are rejected by
the Trustee for failure to comply with the requirements of this Section 4.06,
the Trustee shall return such request to the appropriate DTC Participant with a
copy to DTC with an explanation as to the reason for such rejection.

         (d) To the extent, if any, that principal distributions to be made to
the Special Retail Certificates on a Distribution Date exceed the aggregate
amount of principal distribution requests for such Class which have been
received on or before the applicable Record Date, as provided in Section 4.06(a)
above, additional Special Retail Certificates will be selected to receive
mandatory principal distributions in lots equal to $1,000 in accordance with the
then-applicable Random Lot procedures of DTC, and the then-applicable procedures
of the DTC Participants and Indirect DTC Participants representing the Holders
(which procedures may or may not be by random lot). The Trustee shall notify DTC
of the aggregate amount of the mandatory principal distribution to be made on
the next Distribution Date. DTC shall then allocate such aggregate amount among
the DTC Participants on a Random Lot basis. Each DTC Participant and, in turn,
each Indirect DTC Participant will then select, in accordance with its own
procedures, Special Retail Certificates from among those held in its accounts to
receive mandatory principal distributions, such that the total amount of
principal distributed to the Special Retail Certificates so selected is equal to
the aggregate amount of such mandatory distributions allocated to such DTC
Participant by DTC and to such Indirect DTC Participant by its related DTC
Participant, as the case may be. DTC Participants and Indirect DTC Participants
that hold Special Retail Certificates selected for mandatory principal
distributions are required to provide notice of such mandatory distributions to
the affected Holders. The Certificate Administrator shall notify the Trustee of


                                       52
<PAGE>

the amount of principal distributions to be made on each Distribution Date in a
timely manner such that the Trustee may fulfill its obligations under the
Depositary Agreement.

         (e) Notwithstanding any provisions herein to the contrary, on each
Distribution Date on and after the earlier of (i) the Credit Support Depletion
Date and (ii) the date on which any loss is allocated to the Underlying
Certificates by Pro Rata Allocation, distributions in reduction of the Class
Principal Balance of the Special Retail Certificates will be made pro rata among
the Holders of the Special Retail Certificates and will not be made in integral
multiples of $1,000 nor pursuant to requests for distribution as permitted by
Section 4.06(a) or by mandatory distributions as provided for by Section
4.06(d).

         (f) In the event that Definitive Certificates representing Special
Retail Certificates are issued pursuant to Section 5.09, an amendment to this
Agreement, which may be approved without the consent of any Certificateholders,
shall establish procedures relating to the manner in which distributions in
reduction of the Class Principal Balance of the Special Retail Certificates are
to be made; provided that such procedures shall be consistent, to the extent
practicable and customary for certificates similar to the Special Retail
Certificates, with the provisions of this Section 4.06.

                                   ARTICLE V

                                The Certificates

Section 5.01.     The Certificates.

         (a) The Certificates shall be substantially in the forms set forth in
Exhibit A and B with the additional insertion from Exhibit H attached hereto,
and shall be executed by the Trustee on behalf of the Trust, authenticated by
the Trustee (or any duly appointed Authenticating Agent) and delivered (i) upon
and pursuant to the order of the Company and (ii) upon receipt by the Trustee of
the documents specified in Section 2.01. The Certificates shall be issuable in
Authorized Denominations. Certificates shall be executed by manual or facsimile
signature on behalf of the Trust by authorized officers of the Trustee.
Certificates bearing the manual or facsimile signatures of individuals who were
at the time of execution the proper officers of the Trustee shall bind the
Trust, notwithstanding that such individuals or any of them have ceased to hold
such offices prior to the authentication and delivery of such Certificates or
did not hold such offices at the date of such Certificates. No Certificate shall
be entitled to any benefit under this Agreement, or be valid for any purpose,
unless there appears on such Certificate a certificate of authentication
substantially in the form provided for herein executed by the Trustee or any
Authenticating Agent by manual signature, and such certificate upon any
Certificate shall be conclusive evidence, and the only evidence, that such
Certificate has been duly authenticated and delivered hereunder. All
Certificates shall be dated the date of their authentication.

         (b) The following definitions apply for purposes of this Section 5.01:
"Disqualified Organization" means any Person which is not a Permitted
Transferee, but does not include any "Pass-Through Entity" which owns or holds a
Residual Certificate and of which a Disqualified Organization, directly or
indirectly, may be a stockholder, partner or beneficiary; "Pass-Through Entity"


                                       53
<PAGE>

means any regulated investment company, real estate investment trust, common
trust fund, partnership, trust or estate, and any organization to which Section
1381 of the Code applies; "Ownership Interest" means, with respect to any
Residual Certificate, any ownership or security interest in such Residual
Certificate, including any interest in a Residual Certificate as the Holder
thereof and any other interest therein whether direct or indirect, legal or
beneficial, as owner or as pledgee; "Transfer" means any direct or indirect
transfer or sale of, or directly or indirectly transferring or selling any
Ownership Interest in a Residual Certificate; and "Transferee" means any Person
who is acquiring by Transfer any Ownership Interest in a Residual Certificate.

         (c) Restrictions on Transfers of the Residual Certificates to
Disqualified Organizations are set forth in this Section 5.01(c).

         (i) Each Person who has or who acquires any Ownership Interest in a
Residual Certificate shall be deemed by the acceptance or acquisition of such
Ownership Interest to have agreed to be bound by the following provisions and to
have irrevocably authorized the Trustee or its designee under clause (iii)(A)
below to deliver payments to a Person other than such Person and to negotiate
the terms of any mandatory sale under clause (iii)(B) below and to execute all
instruments of transfer and to do all other things necessary in connection with
any such sale. The rights of each Person acquiring any Ownership Interest in a
Residual Certificate are expressly subject to the following provisions:

         (A) Each Person holding or acquiring any Ownership Interest in a
Residual Certificate shall be a Permitted Transferee and shall promptly notify
the Trustee of any change or impending change in its status as a Permitted
Transferee.

         (B) In connection with any proposed Transfer of any Ownership Interest
in a Residual Certificate to a U.S. Person, the Trustee shall require delivery
to it, and shall not register the Transfer of any Residual Certificate until its
receipt of (1) an affidavit and agreement (a "Transferee Affidavit and
Agreement") attached hereto as Exhibit J from the proposed Transferee, in form
and substance satisfactory to the Company, representing and warranting, among
other things, that it is not a Non-U.S. Person, that such transferee is a
Permitted Transferee, that it is not acquiring its Ownership Interest in the
Residual Certificate that is the subject of the proposed Transfer as a nominee,
trustee or agent for any Person who is not a Permitted Transferee, that for so
long as it retains its Ownership Interest in a Residual Certificate, it will
endeavor to remain a Permitted Transferee, and that it has reviewed the
provisions of this Section 5.01(c) and agrees to be bound by them, and (2) a
certificate, attached hereto as Exhibit I, from the Holder wishing to transfer
the Residual Certificate, in form and substance satisfactory to the Company,
representing and warranting, among other things, that no purpose of the proposed
Transfer is to allow such Holder to impede the assessment or collection of tax.

         (C) Notwithstanding the delivery of a Transferee Affidavit and
Agreement by a proposed Transferee under clause (B) above, if the Trustee has


                                       54
<PAGE>

actual knowledge that the proposed Transferee is not a Permitted Transferee, no
Transfer of an Ownership Interest in a Residual Certificate to such proposed
Transferee shall be effected.

         (D) Each Person holding or acquiring any Ownership Interest in a
Residual Certificate agrees by holding or acquiring such Ownership Interest (i)
to require a Transferee Affidavit and Agreement from any other Person to whom
such Person attempts to transfer its Ownership Interest and to provide a
certificate to the Trustee in the form attached hereto as Exhibit J; (ii) to
obtain the express written consent of the Company prior to any transfer of such
Ownership Interest, which consent may be withheld in the Company's sole
discretion; and (iii) to provide a certificate to the Trustee in the form
attached hereto as Exhibit I.

         (ii) The Trustee shall register the Transfer of any Residual
Certificate only if it shall have received the Transferee Affidavit and
Agreement, a certificate of the Holder requesting such transfer in the form
attached hereto as Exhibit J and all of such other documents as shall have been
reasonably required by the Trustee as a condition to such registration.

         (iii) (A) If any "disqualified organization" (as defined in Section
860E(e)(5) of the Code) shall become a holder of a Residual Certificate, then
the last preceding Permitted Transferee shall be restored, to the extent
permitted by law, to all rights and obligations as Holder thereof retroactive to
the date of registration of such Transfer of such Residual Certificate. If any
Non-U.S. Person shall become a holder of a Residual Certificate, then the last
preceding holder which is a U.S. Person shall be restored, to the extent
permitted by law, to all rights and obligations as Holder thereof retroactive to
the date of registration of the Transfer to such Non-U.S. Person of such
Residual Certificate. If a transfer of a Residual Certificate is disregarded
pursuant to the provisions of Treasury Regulations Section 1.860E-1 or Section
1.860G-3, then the last preceding Permitted Transferee shall be restored, to the
extent permitted by law, to all rights and obligations as Holder thereof
retroactive to the date of registration of such Transfer of such Residual
Certificate. Neither the Trust nor the Trustee shall be under any liability to
any Person for any registration of Transfer of a Residual Certificate that is in
fact not permitted by this Section 5.01(c) or for making any payments due on
such Certificate to the holder thereof or for taking any other action with
respect to such holder under the provisions of this Agreement.

         (B) If any purported Transferee shall become a Holder of a Residual
Certificate in violation of the restrictions in this Section 5.01(c) and to the
extent that the retroactive restoration of the rights of the Holder of such
Residual Certificate as described in clause (iii)(A) above shall be invalid,
illegal or unenforceable, then the Company shall have the right, without notice
to the Holder or any prior Holder of such Residual Certificate, to sell such
Residual Certificate to a purchaser selected by the Company on such terms as the
Company may choose. Such purported Transferee shall promptly endorse and deliver


                                       55
<PAGE>

each Residual Certificate in accordance with the instructions of the Company.
Such purchaser may be the Company itself or any affiliate of the Company. The
proceeds of such sale, net of the commissions (which may include commissions
payable to the Company or its affiliates), expenses and taxes due, if any, shall
be remitted by the Company to such purported Transferee. The terms and
conditions of any sale under this clause (iii)(B) shall be determined in the
sole discretion of the Company, and the Company shall not be liable to any
Person having an Ownership Interest in a Residual Certificate as a result of its
exercise of such discretion.

         (iv) The Company, on behalf of the Trustee, shall make available, upon
written request from the Trustee, all information necessary to compute any tax
imposed (A) as a result of the Transfer of an Ownership Interest in a Residual
Certificate to any Person who is not a Permitted Transferee, including the
information regarding "excess inclusions" of such Residual Certificates required
to be provided to the Internal Revenue Service and certain Persons as described
in Treasury Regulation Section 1.860D-1(b)(5), and (B) as a result of any
regulated investment company, real estate investment trust, common trust fund,
partnership, trust, estate or organizations described in Section 1381 of the
Code having as among its record holders at any time any Person who is not a
Permitted Transferee. Reasonable compensation for providing such information may
be required by the Company from such Person.

         (v) The provisions of this Section 5.01 set forth prior to this Section
(v) may be modified, added to or eliminated by the Company and the Trustee,
provided that there shall have been delivered to the Trustee the following:

         (A) written notification from each of the Rating Agencies to the effect
that the modification, addition to or elimination of such provisions will not
cause such Rating Agency to downgrade its then-current Ratings of the
Certificates (determined in the case of the Insured Certificates, without giving
effect to the Certificate Insurance Policy); and

         (B) an Opinion of Counsel, in form and substance satisfactory to the
Company (as evidenced by a certificate of the Company), to the effect that such
modification, addition to or absence of such provisions will not cause REMIC I
and REMIC II to cease to qualify as a REMIC and will not create a risk that (1)
REMIC I and REMIC II may be subject to an entity-level tax caused by the
Transfer of any Residual Certificate to a Person which is not a Permitted
Transferee or (2) a Certificateholder or another Person will be subject to a
REMIC-related tax caused by the Transfer of a Residual Certificate to a Person
which is not a Permitted Transferee.

         (vi) The following legend shall appear on all Residual Certificates:

ANY RESALE, TRANSFER OR OTHER DISPOSITION OF THIS CERTIFICATE MAY BE MADE ONLY
IF THE PROPOSED TRANSFEREE PROVIDES A TRANSFER AFFIDAVIT TO THE COMPANY AND THE
TRUSTEE THAT (1) SUCH TRANSFEREE IS NOT EITHER (A) THE UNITED STATES, ANY STATE
OR POLITICAL SUBDIVISION THEREOF, ANY FOREIGN GOVERNMENT, ANY INTERNATIONAL
ORGANIZATION, OR ANY AGENCY OR INSTRUMENTALITY OF ANY OF THE FOREGOING, (B) ANY
ORGANIZATION (OTHER THAN A COOPERATIVE DESCRIBED IN SECTION 521 OF THE CODE)


                                       56
<PAGE>

WHICH IS EXEMPT FROM THE TAX IMPOSED BY CHAPTER 1 OF THE CODE UNLESS SUCH
ORGANIZATION IS SUBJECT TO THE TAX IMPOSED BY SECTION 511 OF THE CODE, (C) ANY
ORGANIZATION DESCRIBED IN SECTION 1381(a)(2)(C) OF THE CODE (ANY SUCH PERSON
DESCRIBED IN THE FOREGOING CLAUSES (A), (B), OR (C) BEING HEREINAFTER REFERRED
TO AS A "DISQUALIFIED ORGANIZATION"), OR (D) AN AGENT OF A DISQUALIFIED
ORGANIZATION AND (2) NO PURPOSE OF SUCH TRANSFER IS TO ENABLE THE TRANSFEROR TO
IMPEDE THE ASSESSMENT OR COLLECTION OF TAX. SUCH AFFIDAVIT SHALL INCLUDE CERTAIN
REPRESENTATIONS AS TO THE FINANCIAL CONDITION OF THE PROPOSED TRANSFEREE.
NOTWITHSTANDING THE REGISTRATION IN THE CERTIFICATE REGISTER OF ANY TRANSFER,
SALE OR OTHER DISPOSITION OF THIS CLASS R CERTIFICATE TO A DISQUALIFIED
ORGANIZATION OR AN AGENT OF A DISQUALIFIED ORGANIZATION, SUCH REGISTRATION SHALL
BE DEEMED TO BE OF NO LEGAL FORCE OR EFFECT WHATSOEVER AND SUCH PERSON SHALL NOT
BE DEEMED TO BE A CERTIFICATEHOLDER FOR ANY PURPOSE HEREUNDER, INCLUDING, BUT
NOT LIMITED TO, THE RECEIPT OF DISTRIBUTIONS ON THIS CERTIFICATE. EACH HOLDER OF
THE CLASS R CERTIFICATE BY ACCEPTANCE OF THIS CERTIFICATE SHALL BE DEEMED TO
HAVE CONSENTED TO THE PROVISIONS OF THIS PARAGRAPH.

         (vii) The Tax Matters Person for each of REMIC I and REMIC II, while
not a Disqualified Organization, shall be the tax matters person for the related
REMIC within the meaning of Section 6231(a)(7) of the Code and Treasury
Regulation Section 1.860F-4(d).

         (d) In the case of any Residual Certificate presented for registration
in the name of any Person, the Trustee shall require (i) a Transferee Affidavit
and Agreement which includes the representation set forth in paragraph 18 of the
form attached hereto as Exhibit J and (ii) only if the representation set forth
in such paragraph 18 indicates that a Benefit Plan Opinion is delivered in
connection therewith, a Benefit Plan Opinion.

Section 5.02. Certificates Issuable in Classes; Distributions of Principal and
Interest; Authorized Denominations. The aggregate principal amount of the
Certificates that may be authenticated and delivered under this Agreement is
limited to the aggregate Class Principal Balance of the Underlying Certificates
as of the Closing Date, as specified in the Preliminary Statement to this
Agreement, except for Certificates authenticated and delivered upon registration
of transfer of, or in exchange for, or in lieu of, other Certificates pursuant
to Section 5.03. Such aggregate principal amount shall be allocated among one or
more Classes having designations, types of interests, initial per annum
Certificate Interest Rates, initial Class Principal Balances and Final Maturity
Dates as specified in the Preliminary Statement to this Agreement. The aggregate
Percentage Interest of each Class of Certificates of which the Class Principal
Balance equals zero as of the Cut-Off Date that may be authenticated and
delivered under this Agreement is limited to 100%. Certificates shall be issued
in Authorized Denominations.

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<PAGE>

Section 5.03. Registration of Transfer and Exchange of Certificates. The Trustee
shall cause to be maintained at one of its offices or at its designated agent, a
Certificate Register in which there shall be recorded the name and address of
each Certificateholder. Subject to such reasonable rules and regulations as the
Trustee may prescribe, the Certificate Register shall be amended from time to
time by the Trustee or its agent to reflect notice of any changes received by
the Trustee or its agent pursuant to Section 10.06. The Trustee hereby appoints
itself as the initial Certificate Registrar.

         Upon surrender for registration of transfer of any Certificate to the
Trustee at the Corporate Trust Office of the Trustee, or such other address or
agency as may hereafter be provided to the Certificate Administrator in writing
by the Trustee, the Trustee shall execute, and the Trustee or any Authenticating
Agent shall authenticate and deliver, in the name of the designated transferee
or transferees, one or more new Certificates of Authorized Denominations. At the
option of the Certificateholders, Certificates may be exchanged for other
Certificates in Authorized Denominations of like Certificate Principal Balance
or Percentage Interest, as applicable, upon surrender of the Certificates to be
exchanged at any such office or agency. Whenever any Certificates are so
surrendered for exchange, the Trustee on behalf of the Trust shall execute, and
the Trustee, or any Authenticating Agent, shall authenticate and deliver, the
Certificates which the Certificateholder making the exchange is entitled to
receive. Every Certificate presented or surrendered for transfer shall (if so
required by the Trustee or any Authenticating Agent) be duly endorsed by, or be
accompanied by a written instrument of transfer in form satisfactory to the
Trustee or any Authenticating Agent and duly executed by, the Holder thereof or
such Holder's attorney duly authorized in writing.

         A reasonable service charge may be made for any such exchange or
transfer of Certificates, and the Trustee may require payment of a sum
sufficient to cover any tax or governmental charge that may be imposed in
connection with any exchange or transfer of Certificates.

         All Certificates surrendered for exchange or transfer shall be
cancelled by the Trustee or any Authenticating Agent.

Section 5.04. Mutilated, Destroyed, Lost or Stolen Certificates. If (i) any
mutilated Certificate is surrendered to the Trustee or any Authenticating Agent,
or (ii) the Trustee or any Authenticating Agent receives evidence to their
satisfaction of the destruction, loss or theft of any Certificate, and there is
delivered to the Trustee or any Authenticating Agent (and with respect to the
Insured Certificates, the Certificate Insurer) such security or indemnity as may
be required by them to save each of them and the Trust harmless, then, in the
absence of notice to the Trustee or any Authenticating Agent that such
Certificate has been acquired by a protected purchaser, the Trustee shall
execute and the Trustee or any Authenticating Agent shall authenticate and
deliver, in exchange for or in lieu of any such mutilated, destroyed, lost or
stolen Certificate, a new Certificate of like Certificate Principal Balance or
Percentage Interest as applicable. Upon the issuance of any new Certificate
under this Section 5.04, the Trustee or any Authenticating Agent may require the
payment of a sum sufficient to cover any tax or other governmental charge that
may be imposed in relation thereto and any other expenses (including the fees
and expenses of the Trustee or any Authenticating Agent) connected therewith.
Any replacement Certificate issued pursuant to this Section 5.04 shall
constitute complete and indefeasible evidence of ownership in REMIC II (or with


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<PAGE>

respect to the Class R Certificates, the residual ownership interests in REMIC
I) as if originally issued, whether or not the lost or stolen Certificate shall
be found at any time.

Section 5.05. Persons Deemed Owners. The Company, the Certificate Administrator,
the Trust, the Trustee, the Delaware Trustee, the Certificate Insurer (with
respect to the Insured Certificates) and any agent of any of them may treat the
Person in whose name any Certificate is registered as the owner of such
Certificate for the purpose of receiving distributions pursuant to Section 4.01
and Section 4.04 and (except as provided in the definition of "Certificateholder
or Holder") for all other purposes whatsoever, and neither the Company, the
Certificate Administrator, the Trust, the Trustee, the Delaware Trustee, the
Certificate Registrar nor any agent of the Company, the Certificate
Administrator, the Trust, the Trustee or the Delaware Trustee shall be affected
by notice to the contrary.

Section 5.06. Temporary Certificates. Upon the initial issuance of the
Certificates, the Trustee on behalf of the Trust may execute, and the Trustee or
any Authenticating Agent shall authenticate and deliver, temporary Certificates
which are printed, lithographed, typewritten or otherwise produced, in any
Authorized Denomination, of the tenor of the definitive Certificates in lieu of
which they are issued and with such variations in form from the forms of the
Certificates set forth as Exhibits A, B and H hereto as the Trustee's officers
executing such Certificates may determine, as evidenced by their execution of
the Certificates. Notwithstanding the foregoing, the Certificates may remain in
the form of temporary Certificates.

         If temporary Certificates are issued, the Trustee shall cause
definitive Certificates to be prepared within ten Business Days after the
Closing Date or as soon as practicable thereafter. After preparation of
definitive Certificates, the temporary Certificates shall be exchangeable for
definitive Certificates upon surrender of the temporary Certificates at the
office or agency of the Trustee to be maintained as provided in Section 5.10
hereof, without charge to the holder. Any tax or governmental charge that may be
imposed in connection with any such exchange shall be borne by the Certificate
Administrator. Upon surrender for cancellation of any one or more temporary
Certificates, the Trustee on behalf of the Trust shall execute and the Trustee
or any Authenticating Agent shall authenticate and deliver in exchange therefor
a like principal amount of definitive Certificates of Authorized Denominations.
Until so exchanged, the temporary Certificates shall in all respects be entitled
to the same benefits under this Agreement as definitive Certificates.

Section 5.07. Book-Entry for Book-Entry Certificates. Notwithstanding the
foregoing, the Book-Entry Certificates, upon original issuance, shall be issued
in the form of one or more typewritten Certificates of Authorized Denomination
representing the Book-Entry Certificates, to be delivered to DTC, the initial
Clearing Agency, by, or on behalf of, the Company. The Book-Entry Certificates
shall initially be registered on the Certificate Register in the name of Cede &
Co., the nominee of DTC, as the initial Clearing Agency, and no Beneficial
Holder shall receive a definitive certificate representing such Beneficial
Holder's interest in any Class of Book-Entry Certificate, except as provided
above and in Section 5.09. Each Book-Entry Certificate shall bear the following
legend:

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<PAGE>

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Unless and until definitive, fully registered Book-Entry Certificates (the
"Definitive Certificates") have been issued to the Beneficial Holders pursuant
to Section 5.09:

         (a) the provisions of this Section 5.07 shall be in full force and
effect with respect to the Book-Entry Certificates;

         (b) the Certificate Administrator and the Trustee may deal with the
Clearing Agency for all purposes with respect to the Book-Entry Certificates
(including the making of distributions on the Book-Entry Certificates) as the
sole Certificateholder;

         (c) to the extent that the provisions of this Section 5.07 conflict
with any other provisions of this Agreement, the provisions of this Section 5.07
shall control; and

         (d) the rights of the Beneficial Holders shall be exercised only
through the Clearing Agency and the DTC Participants and shall be limited to
those established by law and agreements between such Beneficial Holders and the
Clearing Agency and/or the DTC Participants. Pursuant to the Depositary
Agreement, unless and until Definitive Certificates are issued pursuant to
Section 5.09, the initial Clearing Agency will make book-entry transfers among
the DTC Participants and receive and transmit distributions of principal and
interest on the related Class of Book-Entry Certificates to such DTC
Participants.

         For purposes of any provision of this Agreement requiring or permitting
actions with the consent of, or at the direction of, Holders of Book-Entry
Certificates evidencing a specified Percentage Interest, such direction or
consent may be given by the Clearing Agency at the direction of Beneficial
Holders owning Book-Entry Certificates evidencing the requisite Percentage
Interest represented by the Book-Entry Certificates. The Clearing Agency may
take conflicting actions with respect to the Book-Entry Certificates to the
extent that such actions are taken on behalf of the Beneficial Holders.

Section 5.08. Notices to Clearing Agency. Whenever notice or other communication
to the Certificateholders is required under this Agreement, unless and until
Definitive Certificates shall have been issued to the related Certificateholders
pursuant to Section 5.09, the Trustee shall give all such notices and
communications specified herein to be given to Holders of the Book-Entry
Certificates to the Clearing Agency which shall give such notices and
communications to the related DTC Participants in accordance with its applicable
rules, regulations and procedures.

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<PAGE>

Section 5.09. Definitive Certificates. If (a) the Certificate Administrator
notifies the Trustee in writing that the Clearing Agency is no longer willing or
able to discharge properly its responsibilities under the Depositary Agreement
with respect to the Book-Entry Certificates and the Trustee or the Certificate
Administrator is unable to locate a qualified successor, (b) the Certificate
Administrator, at its option, advises the Trustee in writing that it elects to
terminate the book-entry system with respect to the Book-Entry Certificates
through the Clearing Agency or (c) after the occurrence of an Event of Default,
Certificateholders holding Book-Entry Certificates evidencing Percentage
Interests aggregating not less than 66% of the aggregate Class Principal Balance
of such Certificates advise the Trustee and the Clearing Agency through DTC
Participants in writing that the continuation of a book-entry system with
respect to the Book-Entry Certificates through the Clearing Agency is no longer
in the best interests of the Certificateholders with respect to such
Certificates, the Trustee shall notify all Certificateholders of Book-Entry
Certificates of the occurrence of any such event and of the availability of
Definitive Certificates. Upon surrender to the Trustee of the Book-Entry
Certificates by the Clearing Agency, accompanied by registration instructions
from the Clearing Agency for registration, the Trustee on behalf of the Trust
shall execute and the Trustee or any Authenticating Agent shall authenticate and
deliver the Definitive Certificates. Neither the Company, the Certificate
Administrator, the Trust nor the Trustee shall be liable for any delay in
delivery of such instructions and may conclusively rely on, and shall be
protected in relying on, such instructions. Upon the issuance of Definitive
Certificates for all of the Certificates all references herein to obligations
imposed upon or to be performed by the Clearing Agency shall be deemed to be
imposed upon and performed by the Trustee, to the extent applicable with respect
to such Definitive Certificates, and the Trustee shall recognize the Holders of
Definitive Certificates as Certificateholders hereunder.

Section 5.10. Office for Transfer of Certificates. The Trustee shall maintain in
New York, New York, an office or agency where Certificates may be surrendered
for registration of transfer or exchange. The Corporate Trust Office is
initially designated for said purposes.

Section 5.11. Nature of Certificates. The Certificates shall be personal
property giving only the rights specifically set forth therein and in this
Agreement. The Certificates shall have no preemptive or similar rights and when
issued and delivered to the Holders against payment of the purchase price
therefor will be fully paid and nonassessable by the Trust. The Holders of the
Certificates, in their capacities as such, shall be entitled to the same
limitation of personal liability extended to stockholders of private
corporations for profit organized under the General Corporation Law of the State
of Delaware. THE RECEIPT AND ACCEPTANCE OF A CERTIFICATE OR ANY INTEREST THEREIN
BY OR ON BEHALF OF A HOLDER OR ANY BENEFICIAL OWNER, WITHOUT ANY SIGNATURE OR
FURTHER MANIFESTATION OF ASSENT, SHALL CONSTITUTE THE UNCONDITIONAL ACCEPTANCE
BY THE HOLDER AND ALL OTHERS HAVING A BENEFICIAL INTEREST IN SUCH CERTIFICATE OF
ALL THE TERMS AND PROVISIONS OF THIS AGREEMENT, AND SHALL CONSTITUTE THE
AGREEMENT OF THE TRUST, SUCH HOLDER AND SUCH OTHERS THAT THE TERMS AND
PROVISIONS OF THIS AGREEMENT SHALL BE BINDING, OPERATIVE AND EFFECTIVE AS
BETWEEN THE TRUST AND SUCH HOLDER AND SUCH OTHERS.



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                                   ARTICLE VI

                  The Company and the Certificate Administrator

Section 6.01. Liability of the Company and the Certificate Administrator. The
Company and the Certificate Administrator shall be liable in accordance herewith
only to the extent of the obligations specifically imposed upon and undertaken
by the Company or the Certificate Administrator, as applicable, herein.

Section 6.02. Merger or Consolidation of the Company, or the Certificate
Administrator. Any Corporation into which the Company or the Certificate
Administrator may be merged or consolidated, or any Corporation resulting from
any merger, conversion or consolidation to which the Company or the Certificate
Administrator shall be a party, or any Corporation succeeding to the business of
the Company or the Certificate Administrator, shall be the successor of the
Company or the Certificate Administrator hereunder, without the execution or
filing of any paper or any further act on the part of any of the parties hereto,
anything herein to the contrary notwithstanding.

Section 6.03. Limitation on Liability of the Company, the Certificate
Administrator and Others. Neither the Company nor the Certificate Administrator
nor any of the directors, officers, employees or agents of the Company or the
Certificate Administrator shall be under any liability to the Trust, the Holders
of the REMIC I Regular Interests or the Certificateholders for any action taken
by such Person or for such Person's refraining from the taking of any action in
good faith pursuant to this Agreement, or for errors in judgment; provided,
however, that this provision shall not protect the Company, the Certificate
Administrator or any such Person against any liability which would otherwise be
imposed by reason of willful misfeasance, bad faith or gross negligence in the
performance of duties or by reason of reckless disregard of duties and
obligations hereunder. The Company, the Certificate Administrator and any
director, officer, employee or agent of the Company or the Certificate
Administrator may rely in good faith on any document of any kind properly
executed and submitted by any Person respecting any matters arising hereunder.
The Company, the Certificate Administrator and any director, officer, employee
or agent of the Company or the Certificate Administrator shall be indemnified by
the Trust and held harmless against any loss, liability or expense incurred in
connection with any legal action relating to this Agreement or the Certificates,
other than any loss, liability or expense relating to any Underlying Certificate
(other than as otherwise permitted in this Agreement) or incurred by reason of
willful misfeasance, bad faith or gross negligence in the performance of duties
hereunder or by reason of reckless disregard of obligations and duties
hereunder. The Company and the Certificate Administrator shall not be under any
obligation to appear in, prosecute or defend any legal action which in its
opinion may involve it in any expense or liability; provided, however, that the
Company or the Certificate Administrator may in its discretion undertake any
such action which it may deem necessary or desirable with respect to the
Underlying Certificates, this Agreement, the Certificates or the rights and
duties of the parties hereto and the interests of the Certificateholders
hereunder. In such event, the legal expenses and costs of such action and any
liability resulting therefrom shall be expenses, costs and liabilities of the
Trust and the Company and the Certificate Administrator shall be entitled to be
reimbursed therefor out of the Certificate Account, as provided by Section 3.05.

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<PAGE>

Section 6.04. The Company and the Certificate Administrator not to Resign. The
Company shall not resign from the obligations and duties (including, without
limitation, its obligations and duties as initial Certificate Administrator)
hereby imposed on it except upon determination that its duties hereunder are no
longer permissible under applicable law. Any successor Certificate Administrator
shall not resign from the obligations and duties hereby imposed on it except
upon determination that its duties hereunder are no longer permissible under
applicable law. Any such determination permitting the resignation of the Company
or any successor Certificate Administrator shall be evidenced by an Opinion of
Counsel to such effect delivered to the Trustee. No such resignation shall
become effective until the Trustee or a successor Certificate Administrator
shall have assumed the Certificate Administrator's responsibilities and
obligations in accordance with Section 7.02 hereof.

         If the Company is no longer acting as Certificate Administrator, then
the successor Certificate Administrator shall give prompt written notice to the
Company of any information received by such successor Certificate Administrator
which affects or relates to an ongoing obligation or right of the Company under
this Agreement.

Section 6.05. Trustee Access. The Certificate Administrator shall afford the
Company and the Trustee, upon reasonable notice, during normal business hours
access to all records maintained by the Certificate Administrator, in respect of
the Mortgage Loans and in respect of its rights and obligations hereunder and
access to such of its officers as are responsible for such obligations. Upon
reasonable request, the Certificate Administrator, shall furnish the Company and
the Trustee with its most recent financial statements (or, for so long as the
Company is the Certificate Administrator, the most recent consolidated financial
statements for the Company appearing in the audited financial statements of
Washington Mutual, Inc., or the entity with whose financial statements the
financial statements of the Company are consolidated) and such other information
as it possesses, and which it is not prohibited by law or, to the extent
applicable, binding obligations to third parties with respect to confidentiality
from disclosing, regarding its business, affairs, property and condition,
financial or otherwise.

                                  ARTICLE VII

                                     Default

Section 7.01. Events of Default. (a) In case one or more of the following Events
of Default by the Certificate Administrator or by a successor Certificate
Administrator shall occur and be continuing, that is to say:

         (i) Any failure by the Certificate Administrator to deposit into the
Certificate Account any payment required to be deposited therein by the
Certificate Administrator under the terms of this Agreement which continues
unremedied for a period of five Business Days after the date upon which written
notice of such failure, requiring the same to be remedied, shall have been given
to the Certificate Administrator by the Trustee or to the Certificate
Administrator and the Trustee by the Holders of Certificates evidencing
Percentage Interests aggregating not less than 25% of REMIC II; or

                                       63
<PAGE>

         (ii) Failure on the part of the Certificate Administrator duly to
observe or perform in any material respect any other of the covenants or
agreements on the part of the Certificate Administrator contained in the
Certificates or in this Agreement which continues unremedied for a period of 60
days after the date on which written notice of such failure, requiring the same
to be remedied, shall have been given to the Certificate Administrator by the
Trustee, or to the Certificate Administrator and the Trustee by the Holders of
Certificates evidencing Percentage Interests aggregating not less than 25% of
REMIC II; or

         (iii) A decree or order of a court or agency or supervisory authority
having jurisdiction in the premises for the appointment of a trustee in
bankruptcy, conservator or receiver or liquidator in any bankruptcy, insolvency,
readjustment of debt, marshalling of assets and liabilities or similar
proceedings, or for the winding-up or liquidation of its affairs, shall have
been entered against the Certificate Administrator and such decree or order
shall have remained in force undischarged or unstayed for a period of 60 days;
or

         (iv) The Certificate Administrator shall consent to the appointment of
a trustee in bankruptcy, conservator or receiver or liquidator in any
bankruptcy, insolvency, readjustment of debt, marshalling of assets and
liabilities or similar proceedings of or relating to the Certificate
Administrator or of or relating to all or substantially all of its property; or

         (v) The Certificate Administrator shall admit in writing its inability
to pay its debts generally as they become due, file a petition to take advantage
of any applicable bankruptcy, insolvency or reorganization statute, make an
assignment for the benefit of its creditors, or voluntarily suspend payment of
its obligations;

then, and in each and every such case, so long as an Event of Default shall not
have been remedied, either the Trustee or the Holders of Certificates evidencing
Percentage Interests aggregating not less than 25% of REMIC II, by notice in
writing to the Company and the Certificate Administrator (and to the Trustee if
given by the Certificateholders, in which case such notice shall set forth
evidence reasonably satisfactory to the Trustee that such Event of Default has
occurred and shall not have been remedied) may terminate all of the rights
(other than its right to reimbursement for advances) and obligations of the
Certificate Administrator, including its right to the Certificate Administrator
Fee, under this Agreement and in and to the Underlying Certificates and the
proceeds thereof, if any. Such determination shall be final and binding. On or
after the receipt by the Certificate Administrator of such written notice, all
authority and power of the Certificate Administrator under this Agreement,
whether with respect to the Certificates or the Underlying Certificates or
otherwise, shall pass to and be vested in the Trustee pursuant to and under this
Section 7.01; and, without limitation, the Trustee is hereby authorized and
empowered to execute and deliver, on behalf of the Certificate Administrator, as
attorney-in-fact or otherwise, any and all documents and other instruments, and
to do or accomplish all other acts or things necessary or appropriate to effect
the purposes of such notice of termination. The Certificate Administrator agrees
to cooperate with the Trustee in effecting the termination of the Certificate
Administrator's responsibilities and rights hereunder, including, without
limitation, the transfer to the Trustee for administration by it of all cash


                                       64
<PAGE>

amounts which shall at the time be credited by the Certificate Administrator to
the Certificate Account or thereafter be received with respect to the Underlying
Certificates.

         (b) In case one or more of the following Events of Default by the
Company shall occur and be continuing, that is to say:

         (i) Failure on the part of the Company duly to observe or perform in
any material respect any of the covenants or agreements on the part of the
Company contained in the Certificates or in this Agreement which continues
unremedied for a period of 60 days after the date on which written notice of
such failure, requiring the same to be remedied, shall have been given to the
Company by the Trustee, or to the Company and the Trustee by the Holders of
Certificates evidencing Percentage Interests aggregating not less than 25% of
REMIC II; or

         (ii) A decree or order of a court or agency or supervisory authority
having jurisdiction in the premises for the appointment of a trustee in
bankruptcy, conservator or receiver or liquidator in any bankruptcy, insolvency,
readjustment of debt, marshalling of assets and liabilities or similar
proceedings, or for the winding-up or liquidation of its affairs, shall have
been entered against the Company and such decree or order shall have remained in
force undischarged or unstayed for a period of 60 days; or

         (iii) The Company shall consent to the appointment of a trustee in
bankruptcy, conservator or receiver or liquidator in any bankruptcy, insolvency,
readjustment of debt, marshalling of assets and liabilities or similar
proceedings of or relating to the Company or of or relating to all or
substantially all of its property; or

         (iv) The Company shall admit in writing its inability to pay its debts
generally as they become due, file a petition to take advantage of any
applicable bankruptcy, insolvency or reorganization statute, make an assignment
for the benefit of creditors, or voluntarily suspend payment of its obligations;

then, and in each and every such case, so long as such Event of Default shall
not have been remedied, the Holders of Certificates evidencing Percentage
Interests aggregating not less than 25% of REMIC II, by notice in writing to the
Company and the Trustee, may direct the Trustee in accordance with Section 10.03
to institute an action, suit or proceeding in its own name as Trustee hereunder
to enforce the Company's obligations hereunder.

         (c) In any circumstances in which this Agreement states that
Certificateholders owning Certificates evidencing a certain percentage
Percentage Interest in REMIC II may take certain action, such action shall be
taken by the Trustee, but only if the requisite percentage of Certificateholders
required under this Agreement for taking like action or giving like instruction
to the Trustee under this Agreement shall have so directed the Trustee in
writing.

Section 7.02. Trustee to Act; Appointment of Successor. On and after the date on
which the Certificate Administrator receives a notice of termination pursuant to
Section 7.01 or the Certificate Administrator resigns pursuant to Section 6.04,
the Trustee shall be the successor in all respects to the Certificate
Administrator under this Agreement and with respect to the transactions set
forth or provided for herein and shall have all the rights and powers and be
subject to all the responsibilities, duties and liabilities relating thereto


                                       65
<PAGE>

arising on or after such date of termination or resignation placed on the
Certificate Administrator by the terms and provisions hereof and thereof, and
shall have the same limitations on liability herein granted to the Certificate
Administrator; provided, that the Trustee shall not under any circumstances be
responsible for any representations and warranties of the Company or any
liability incurred by the Certificate Administrator prior to such date of
termination or resignation. As compensation therefor, the Trustee shall be
entitled to all funds relating to the Underlying Certificates which the
Certificate Administrator would have been entitled to retain or to withdraw from
the Certificate Account if the Certificate Administrator had continued to act
hereunder, except for those amounts due to the Certificate Administrator as
reimbursement for amounts previously expended and are otherwise reimbursable
hereunder. Notwithstanding the above, the Trustee may, if it shall be unwilling
to so act, or shall if it is unable to so act, appoint, or petition a court of
competent jurisdiction to appoint, any established housing and home finance
institution having a net worth of not less than $10,000,000 as the successor to
the Certificate Administrator hereunder in the assumption of all or any part of
the responsibilities, duties or liabilities of the Certificate Administrator
hereunder. Pending any such appointment, the Trustee is obligated to act in such
capacity. In connection with such appointment and assumption, the Trustee may
make such arrangements for the compensation of such successor out of payments on
Underlying Certificates as it and such successor shall agree; provided, however,
that no such compensation shall, together with the compensation to the Trustee,
be in excess of that permitted the Certificate Administrator hereunder. The
Trustee and such successor shall take such actions, consistent with this
Agreement, as shall be necessary to effectuate any such succession.

Section 7.03. Notification to Certificateholders. Upon any such termination or
appointment of a successor to the Certificate Administrator, the Trustee shall
give prompt written notice thereof to the Certificateholders at their respective
addresses appearing in the Certificate Register and to the Certificate Insurer.

                                  ARTICLE VIII

                             Concerning the Trustees

Section 8.01.     Duties of Trustees.

         (a) The Trustee, prior to the occurrence of an Event of Default and
after the curing of all Events of Default which may have occurred, undertakes to
perform such duties and only such duties as are specifically set forth in this
Agreement. In case an Event of Default has occurred (which has not been cured or
waived) the Trustee shall exercise such of the rights and powers vested in it by
this Agreement, and use the same degree of care and skill in its exercise as a
prudent person would exercise or use under the circumstances in the conduct of
such person's own affairs.

         (b) The Trustee, upon receipt of all resolutions, certificates,
statements, opinions, reports, documents, orders or other instruments furnished
to it which are specifically required to be furnished to it pursuant to any
provision of this Agreement, shall examine them to determine whether they are in
the form required by this Agreement; provided, however, that the Trustee shall
not be responsible for the accuracy or content of any such certificate,


                                       66
<PAGE>

statement, opinion, report, or other order or instrument furnished by the
Company or Certificate Administrator to the Trustee pursuant to this Agreement.

         (c) No provision of this Agreement shall be construed to relieve the
Trustee or the Delaware Trustee from liability for its own negligent action, its
own negligent failure to act or its own willful misconduct; provided, however,
that:

         (i) Prior to the occurrence of an Event of Default and after the curing
of all such Events of Default which may have occurred, the duties and
obligations of the Trustee shall be determined solely by the express provisions
of this Agreement;

         (ii) Neither the Trustee nor the Delaware Trustee shall be liable
except for the performance of such duties and obligations as are specifically
set forth in this Agreement, no implied covenants or obligations shall be read
into this Agreement against the Trustee or the Delaware Trustee, and, in the
absence of bad faith on the part of the Trustee or the Delaware Trustee, such
trustee may conclusively rely, as to the truth of the statements and the
correctness of the opinions expressed therein, upon any certificates or opinions
furnished to such trustee and conforming to the requirements of this Agreement;
and

         (iii) Neither the Trustee nor the Delaware Trustee shall be personally
liable with respect to any action taken or omitted to be taken by it in good
faith in accordance with the direction of the Certificateholders holding
Certificates which evidence Percentage Interests aggregating not less than 25%
of REMIC II (or, in the case of the action described in Section 8.01(f), which
evidence Percentage Interests aggregating more than 50% of REMIC II) relating to
the time, method and place of conducting any proceeding for any remedy available
to such trustee, or relating to the exercise of any trust or power conferred
upon such trustee under this Agreement.

         (d) Within ten Business Days after the occurrence of any Event of
Default known to the Trustee, the Trustee shall transmit by mail to the Rating
Agencies notice of each Event of Default. Within 90 days after the occurrence of
any Event of Default known to the Trustee, the Trustee shall transmit by mail to
all Certificateholders (with a copy to the Rating Agencies) notice of each Event
of Default, unless such Event of Default shall have been cured or waived;
provided, however, the Trustee shall be protected in withholding such notice if
and so long as a Responsible Officer of the Trustee in good faith determines
that the withholding of such notice is in the best interests of the
Certificateholders; and provided, further, that in the case of any Event of
Default of the character specified in Section 7.01(i) and Section 7.01(ii) no
such notice to Certificateholders or to the Rating Agencies shall be given until
at least 30 days after the occurrence thereof.

         (e) Concurrently with the execution hereof, the Trustee shall execute
the Insurance Agreement dated of even date herewith and shall perform its
obligations thereunder in accordance with the terms thereof. The Trustee shall
have no duty to review or otherwise determine the adequacy of the Insurance
Agreement on behalf of the Certificateholders.



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<PAGE>

         (f) The Trustee or the Delaware Trustee, as applicable, shall take or
refrain from taking such action with respect to any proposed amendment to the
Pooling and Servicing Agreement as the Certificateholders holding Certificates
which evidence Percentage Interests aggregating more than 50% of REMIC II shall
so direct in writing; provided, however, that no such act or failure to act
shall: (i) reduce in any manner the amount of, or delay the timing of, payments
received on any Certificate without the consent of the affected
Certificateholder or (ii) amend this Section 8.01(f), without the consent of all
of the Certificateholders then outstanding.

Section 8.02. Certain Matters Affecting the Trustees. Except as otherwise
provided in Section 8.01:

         (i) Each of the Trustee and the Delaware Trustee may request and rely
upon and shall be protected in acting or refraining from acting upon any
resolution, Officer's Certificate, certificate of auditors or any other
certificate, statement, instrument, opinion, report, notice, request, consent,
order, approval, bond or other paper or document believed by it to be genuine
and to have been signed or presented by the proper party or parties;

         (ii) Each of the Trustee and the Delaware Trustee may consult with
counsel and any Opinion of Counsel shall be full and complete authorization and
protection in respect of any action taken or suffered or omitted by it hereunder
in good faith and in accordance with such Opinion of Counsel;

         (iii) Neither the Trustee nor the Delaware Trustee shall be personally
liable for any action taken or omitted by it in good faith and reasonably
believed by it to be authorized or within the discretion or rights or powers
conferred upon it by this Agreement;

         (iv) Prior to the occurrence of an Event of Default hereunder and after
the curing of all Events of Default which may have occurred, neither the Trustee
nor the Delaware Trustee shall be bound to make any investigation into the facts
or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, consent, order, approval, bond or other paper
or document, unless requested in writing to do so by the Holders of Certificates
(including the Certificate Insurer, with respect to the Insured Certificates)
evidencing Percentage Interests aggregating not less than 25% of REMIC II;
provided, however, that if the payment within a reasonable time to the Trustee
or the Delaware Trustee of the costs, expenses or liabilities likely to be
incurred by it in the making of such investigation is, in the opinion of such
trustee, not reasonably assured to such trustee by the security, if any,
afforded to it by the terms of this Agreement, such trustee may require
reasonable indemnity against such expense or liability as a condition to
proceeding;

         (v) Each of the Trustee and the Delaware Trustee may execute the trust
or any of the powers hereunder or perform any duties hereunder either directly
or by or through agents or attorneys selected by it with reasonable care or
designated by the Company;


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<PAGE>

         (vi) Neither the Trustee nor the Delaware Trustee shall be deemed to
have knowledge or notice of any matter, including without limitation an Event of
Default, unless actually known by a Responsible Officer, or unless written
notice thereof referencing this Agreement or the Certificates is received at the
Notice Address of such trustee;

         (vii) In no event shall the Trustee or the Delaware Trustee be held
liable for acts or omissions of the Certificate Administrator or the other
trustee (excepting the Trustee's own actions as Certificate Administrator). No
provision of this Agreement shall require the Trustee or the Delaware Trustee to
expend or risk its own funds or otherwise incur any financial liability in the
performance of any of its duties hereunder (except for the giving of required
notices), or in the exercise of any of its rights or powers, if it shall have
reasonable grounds for believing the repayment of such funds or adequate
indemnity against such risk or liability is not reasonably assured to it;

         (viii) When the Trustee is acting as Certificate Administrator pursuant
to Section 7.02, and to the extent permitted under applicable law, the Trustee
is hereby authorized, in making or disposing of any investment permitted
hereunder, to deal with itself (in its individual capacity) or with any one or
more of its affiliates, whether it or its affiliate is acting as an agent of the
Trustee or of any third person or dealing as principal for its own account; and

         (ix) Except as expressly provided in this Agreement, in no event shall
the Trustee be under any duty or obligation to monitor, determine, investigate
or compel compliance by the Trust with the requirements of the Statutory Trust
Statute.

Section 8.03. Trustees Not Liable for Certificates or Underlying Certificates.
The recitals contained herein (other than those relating to the due
organization, power and authority of the Trustee and the Delaware Trustee) and
in the Certificates (other than the execution of, and certificate of
authentication on, the Certificates) shall be taken as the statements of the
Company or the Trust, as applicable, and neither the Trustee nor the Delaware
Trustee assumes any responsibility for their correctness. Neither the Trustee
nor the Delaware Trustee makes any representations as to the validity or
sufficiency of this Agreement or of the Certificates or any Underlying
Certificate. Neither the Trustee nor the Delaware Trustee shall be accountable
for the use or application by the Company or the Trust, as applicable, of any of
the Certificates or of the proceeds of such Certificates, or for the use or
application of any funds paid to the Certificate Administrator or the Company in
respect of the Underlying Certificates or deposited into the Certificate Account
by the Certificate Administrator or the Company, nor shall the Trustee be
responsible or liable for any delays in receiving amounts due on the Underlying
Certificates.

Section 8.04. Trustees May Own Certificates. The Trustee, the Delaware Trustee
or any agent or affiliate of such trustee, in its individual or any other
capacity, may become the owner or pledgee of Certificates with the same rights
it would have if it were not trustee.

Section 8.05. The Certificate Administrator to Pay Trustees' Fees and Expenses.
Subject to separate written agreements with the Trustee and the Delaware
Trustee, the Certificate Administrator covenants and agrees to, and the

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<PAGE>

Certificate Administrator shall, pay each of the Trustee and the Delaware
Trustee from time to time, and such trustee shall be entitled to payment, for
all services rendered by it in the execution of the trust hereby created and in
the exercise and performance of any of the powers and duties hereunder of such
trustee. Except as otherwise expressly provided herein, the Certificate
Administrator shall pay or reimburse each of the Trustee and the Delaware
Trustee upon such trustee's request for all reasonable expenses and
disbursements incurred or made by such trustee in accordance with any of the
provisions of this Agreement and indemnify such trustee from any loss, liability
or expense incurred by it hereunder (including the reasonable compensation and
the expenses and disbursements of its counsel and of all persons not regularly
in its employ and any expenses which arise out of or are imposed upon the
Trustee or the Delaware Trustee in connection with the creation, operation or
termination of the Trust) except any such expense or disbursement as may arise
from its own negligence or bad faith. Such obligation shall survive the
termination of this Agreement or resignation or removal of the Trustee or the
Delaware Trustee. The Tax Matters Person shall, at its expense, prepare or cause
to be prepared all federal and state income tax and franchise tax and
information returns relating to REMIC I or REMIC II required to be prepared or
filed by the Trustee or the Delaware Trustee and shall indemnify the Trustee and
the Delaware Trustee for any liability of such trustees arising from any error
in such returns.

Section 8.06. Eligibility Requirements for Trustees. The Trustee hereunder shall
at all times be (i) an institution insured by the FDIC, (ii) a Corporation
organized and doing business under the laws of the United States of America or
of any state, authorized under such laws to exercise corporate trust powers,
having a combined capital and surplus of not less than $50,000,000 and subject
to supervision or examination by federal or state authority and (iii) acceptable
to the Rating Agencies. If such Corporation publishes reports of condition at
least annually, pursuant to law or to the requirements of any aforementioned
supervising or examining authority, then for the purposes of this Section 8.06,
the combined capital and surplus of such Corporation shall be deemed to be its
combined capital and surplus as set forth in its most recent report of condition
so published. The Delaware Trustee hereunder shall at all times have its
principal place of business in the State of Delaware and shall satisfy the
applicable requirements under the laws of the State of Delaware authorizing it
to act as the Delaware trustee of the Trust. In case at any time the Trustee or
the Delaware Trustee shall cease to be eligible in accordance with the
provisions of this Section 8.06, such trustee shall resign immediately in the
manner and with the effect specified in Section 8.07.

Section 8.07. Resignation and Removal of Trustees. Each of the Trustee and the
Delaware Trustee may at any time resign and be discharged from the trust hereby
created by giving written notice thereof to the Certificate Administrator and
the Certificate Insurer. Upon receiving such notice of resignation, the
Certificate Administrator shall promptly appoint a successor trustee by written
instrument (subject to the prior written consent of the Certificate Insurer,
which consent shall not be unreasonably withheld), in duplicate, one copy of
which instrument shall be delivered to the resigning trustee and one copy to the
successor trustee. If no successor trustee shall have been so appointed and
shall have accepted appointment within 30 days after the giving of such notice
of resignation, the resigning trustee may petition any court of competent
jurisdiction for the appointment of a successor trustee.

         If at any time the Trustee or the Delaware Trustee shall cease to be
eligible in accordance with the provisions of Section 8.06 and shall fail to

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<PAGE>

resign after written request therefor by the Certificate Administrator, or if at
any time the Trustee or the Delaware Trustee shall become incapable of acting,
or shall be adjudged bankrupt or insolvent, or a receiver of such trustee or of
its property shall be appointed, or any public officer shall take charge or
control of such trustee or of its property or affairs for the purpose of
rehabilitation, conservation or liquidation, then the Certificate Administrator
may remove such trustee and appoint a successor trustee by written instrument
(subject to the prior written consent of the Certificate Insurer, which consent
shall not be unreasonably withheld), in duplicate, copies of which instrument
shall be delivered to the trustee so removed, the trustee continuing in its
capacity and the successor trustee.

         The Holders of Certificates evidencing Percentage Interests aggregating
more than 50% of REMIC II may at any time remove the Trustee or the Delaware
Trustee and appoint a successor trustee by written instrument or instruments, in
triplicate, signed by such Holders or their attorneys in-fact duly authorized,
one complete set of which instruments shall be delivered to the Certificate
Administrator, one complete set to the Trustee so removed and one complete set
to the successor so appointed.

         Any resignation or removal of the Trustee or the Delaware Trustee and
appointment of a successor trustee pursuant to any of the provisions of this
Section 8.07 shall become effective upon acceptance of appointment by the
successor trustee as provided in Section 8.08. Any expenses associated with the
resignation of the Trustee or the Delaware Trustee shall be borne by such
trustee, and any expenses associated with the removal of the Trustee or the
Delaware Trustee shall be borne by the Certificate Administrator.

Section 8.08. Successor Trustee. Any successor trustee appointed as provided in
Section 8.07 shall execute, acknowledge and deliver to the Certificate
Administrator and to its predecessor trustee an instrument accepting such
appointment hereunder, and thereupon the resignation or removal of the
predecessor trustee shall become effective and such successor trustee, without
any further act, deed or conveyance, shall become fully vested with all the
rights, powers, duties and obligations of its predecessor hereunder, with like
effect as if originally named as Trustee or Delaware Trustee herein. The
predecessor shall deliver to the successor trustee all property held by it
hereunder, and the Certificate Administrator and the predecessor trustee shall
execute and deliver such instruments and do such other things as may reasonably
be required for more fully and certainly vesting and confirming in the successor
trustee all such rights, powers, duties and obligations.

         No successor trustee shall accept appointment as provided in this
Section 8.08 unless at the time of such appointment such successor trustee shall
be eligible under the provisions of Section 8.06.

         Upon acceptance of appointment by a successor trustee as provided in
this Section 8.08, the Certificate Administrator shall mail notice of the
succession of such trustee hereunder to (i) all Certificateholders at their
addresses as shown in the Certificate Register, (ii) the Certificate Insurer and
(iii) the Rating Agencies. If the Certificate Administrator fails to mail such
notice within ten days after acceptance of appointment by the successor trustee,
the successor trustee shall cause such notice to be mailed.


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Section 8.09. Merger or Consolidation of Trustee. Any Corporation into which the
Trustee or the Delaware Trustee may be merged or converted or with which it may
be consolidated, or any Corporation resulting from any merger, conversion or
consolidation to which the Trustee or the Delaware Trustee shall be a party, or
any Corporation succeeding to the corporate trust business of such trustee,
shall be the successor of such trustee hereunder, provided such resulting or
successor Corporation shall be eligible under the provisions of Section 8.06,
without the execution or filing of any paper or any further act on the part of
any of the parties hereto, anything herein to the contrary notwithstanding.

Section 8.10. Appointment of Co-Trustee or Separate Trustee. Notwithstanding any
other provisions hereof, at any time, for the purpose of meeting any legal
requirements of any jurisdiction in which any part of the assets of the Trust
may at the time be located, the Certificate Administrator and the Trustee or the
Delaware Trustee, as applicable, acting jointly shall have the power and shall
execute and deliver all instruments to appoint one or more Persons approved by
such trustee to act as co-trustee or co-trustees, jointly with such trustee, or
separate trustee or separate trustees, of all or any part of the assets of the
Trust and to vest in such Person or Persons, in such capacity, such title to the
assets of the Trust, or any part thereof, and, subject to the other provisions
of this Section 8.10, such powers, duties, obligations, rights and trusts as the
Certificate Administrator and the Trustee or the Delaware Trustee, as
applicable, may consider necessary or desirable; provided, that the Trustee or
the Delaware Trustee, as applicable, shall remain liable for all of its
obligations and duties under this Agreement. If the Certificate Administrator
shall not have joined in such appointment within 15 days after the receipt by it
of a request so to do, or in case an Event of Default shall have occurred and be
continuing, the Trustee or the Delaware Trustee, as applicable, alone shall have
the power to make such appointment; provided, that such trustee shall remain
liable for all of its obligations and duties under this Agreement. No co-trustee
or separate trustee hereunder shall be required to meet the terms of eligibility
as a successor trustee under Section 8.06 hereunder and no notice to
Certificateholders of the appointment of co-trustee(s) or separate trustee(s)
shall be required under Section 8.08 hereof.

         In the case of any appointment of a co-trustee or separate trustee
pursuant to this Section 8.10, all rights, powers, duties and obligations
conferred or imposed upon the Trustee or the Delaware Trustee, as applicable,
shall be conferred or imposed upon and exercised or performed by the Trustee or
the Delaware Trustee, as applicable, and such separate trustee or co-trustee
jointly and severally, except to the extent that under any law of any
jurisdiction in which any particular act or acts are to be performed by the
Trustee or the Delaware Trustee, as applicable (whether as Trustee or Delaware
Trustee hereunder or as successor to the Certificate Administrator hereunder),
such trustee shall be incompetent or unqualified to perform such act or acts, in
which event such rights, powers, duties and obligations (including the holding
of title to the assets of the Trust or any portion thereof in any such
jurisdiction) shall be exercised and performed by such separate trustee or
co-trustee at the direction of the Trustee or the Delaware Trustee, as
applicable.

         Any notice, request or other writing given to the Trustee or the
Delaware Trustee shall be deemed to have been given to each of the then related
separate trustee(s) and co-trustee(s), as effectively as if given to each of
them. Every instrument appointing any separate trustee(s) or co-trustee(s) shall
refer to this Agreement and the conditions of this Article VIII. Each separate

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trustee and co-trustee, upon its acceptance of the trusts conferred, shall be
vested with the estates or property specified in its instrument of appointment,
either jointly with the Trustee or the Delaware Trustee, as applicable, or
separately, as may be provided therein, subject to all the provisions of this
Agreement, specifically including every provision of this Agreement relating to
the conduct of, affecting the liability of, or affording protection to, the
Trustee or the Delaware Trustee, as applicable. Every such instrument shall be
filed with the Trustee or the Delaware Trustee, as applicable.

         Any separate trustee or co-trustee may, at any time, constitute the
Trustee or the Delaware Trustee, as applicable, its agent or attorney-in-fact,
with full power and authority, to the extent not prohibited by law, to do any
lawful act under or in respect of this Agreement on its behalf and in its name.
If any separate trustee or co-trustee shall die, become incapable of acting,
resign or be removed, all of its estates, properties, rights, remedies and the
trust shall vest in and be exercised by the Trustee or the Delaware Trustee, as
applicable, to the extent permitted by law, without the appointment of a new or
successor trustee.

Section 8.11. Authenticating Agents. The Trustee may appoint one or more
Authenticating Agents which shall be authorized to act on behalf of the Trustee
in authenticating Certificates. Wherever reference is made in this Agreement to
the authentication of Certificates by the Trustee or the Trustee's certificate
of authentication, such reference shall be deemed to include authentication on
behalf of the Trustee by an Authenticating Agent and a certificate of
authentication executed on behalf of the Trustee by an Authenticating Agent.
Each Authenticating Agent must be acceptable to the Certificate Administrator
and must be a corporation, trust company or banking association organized and
doing business under the laws of the United States of America or of any state,
having an office and place of business in New York, New York, having a combined
capital and surplus of at least $15,000,000, authorized under such laws to do a
trust business and subject to supervision or examination by federal or state
authorities.

         Any corporation into which any Authenticating Agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, conversion or consolidation to which any Authenticating Agent
shall be a party, or any corporation succeeding to the corporate agency business
of any Authenticating Agent, shall continue to be the Authenticating Agent so
long as it shall be eligible in accordance with the provisions of the first
paragraph of this Section 8.11 without the execution or filing of any paper or
any further act on the part of the Trustee or the Authenticating Agent.

         Any Authenticating Agent may at any time resign by giving written
notice of resignation to the Trustee and the Certificate Administrator. The
Trustee may, upon prior written approval of the Certificate Administrator, at
any time terminate the agency of any Authenticating Agent by giving written
notice of termination to such Authenticating Agent and to the Certificate
Administrator. Upon receiving a notice of resignation or upon such a
termination, or in case at any time any Authenticating Agent shall cease to be
eligible in accordance with the provisions of the first paragraph of this
Section 8.11, the Trustee may appoint, upon prior written approval of the
Certificate Administrator, a successor Authenticating Agent, shall give written
notice of such appointment to the Certificate Administrator and shall mail
notice of such appointment to all Certificateholders. Any successor

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<PAGE>

Authenticating Agent upon acceptance of its appointment hereunder shall become
vested with all the rights, powers, duties and responsibilities of its
predecessor hereunder, with like effect as if originally named as Authenticating
Agent. Any reasonable compensation paid to an Authenticating Agent shall be a
reimbursable expense pursuant to Section 8.05 if paid by the Trustee.

Section 8.12. Paying Agents. The Trustee may appoint one or more Paying Agents
which shall be authorized to act on behalf of the Trustee in making withdrawals
from the Certificate Account, and distributions to Certificateholders as
provided in Section 4.01, Section 4.04(a) and Section 9.01(b) to the extent
directed to do so by the Certificate Administrator. Wherever reference is made
in this Agreement to the withdrawal from the Certificate Account by the Trustee,
such reference shall be deemed to include such a withdrawal on behalf of the
Trustee by a Paying Agent. Whenever reference is made in this Agreement to a
distribution by the Trustee or the furnishing of a statement to
Certificateholders by the Trustee, such reference shall be deemed to include
such a distribution or furnishing on behalf of the Trustee by a Paying Agent.
Each Paying Agent shall provide to the Trustee such information concerning the
Certificate Account as the Trustee shall request from time to time. Each Paying
Agent must be reasonably acceptable to the Certificate Administrator and must be
a corporation, trust company or banking association organized and doing business
under the laws of the United States of America or of any state, having an office
and place of business in New York, New York, having a combined capital and
surplus of at least $15,000,000, authorized under such laws to do a trust
business and subject to supervision or examination by federal or state
authorities.

         Any corporation into which any Paying Agent may be merged or converted
or with which it may be consolidated, or any corporation resulting from any
merger, conversion or consolidation to which any Paying Agent shall be a party,
or any corporation succeeding to the corporate agency business of any Paying
Agent, shall continue to be the Paying Agent provided that such corporation
after the consummation of such merger, conversion, consolidation or succession
meets the eligibility requirements of this Section 8.12.

         Any Paying Agent may at any time resign by giving written notice of
resignation to the Trustee and to the Certificate Administrator; provided, that
the Paying Agent has returned to the Certificate Account or otherwise accounted,
to the reasonable satisfaction of the Certificate Administrator, for all amounts
it has withdrawn from the Certificate Account. The Trustee may, upon prior
written approval of the Certificate Administrator, at any time terminate the
agency of any Paying Agent by giving written notice of termination to such
Paying Agent and to the Certificate Administrator. Upon receiving a notice of
resignation or upon such a termination, or in case at any time any Paying Agent
shall cease to be eligible in accordance with the provisions of the first
paragraph of this Section 8.12, the Trustee may appoint, upon prior written
approval of the Certificate Administrator, a successor Paying Agent, shall give
written notice of such appointment to the Certificate Administrator and shall
mail notice of such appointment to all Certificateholders. Any successor Paying
Agent upon acceptance of its appointment hereunder shall become vested with all
the rights, powers, duties and responsibilities of its predecessor hereunder,
with like effect as if originally named as Paying Agent. Any reasonable
compensation paid to any Paying Agent shall be a reimbursable expense pursuant
to Section 8.05 if paid by the Trustee.



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Section 8.13.     Duties of Delaware Trustee.

         (a) The Delaware Trustee is appointed to serve as the trustee of the
Trust in the State of Delaware for the sole purpose of satisfying the
requirement of Section 3807(a) of the Statutory Trust Statute that the Trust
have at least one trustee with a principal place of business in Delaware. It is
understood and agreed by the parties hereto that the Delaware Trustee shall have
none of the duties or liabilities of the Trustee.

         (b) The duties of the Delaware Trustee shall be limited to (i)
accepting legal process served on the Trust in the State of Delaware, (ii) the
execution of any certificates with respect to the Trust required to be filed
with the Secretary of State which the Delaware Trustee is required to execute
under Section 3811 of the Statutory Trust Statute and (iii) such other duties as
are set forth in this Article VIII. To the extent that, at law or in equity, the
Delaware Trustee has duties (including fiduciary duties) and liabilities
relating thereto to the Trust or the Holders of the REMIC I Regular Interests or
the Certificates, it is hereby understood and agreed by the parties hereto that
such duties and liabilities are replaced by the duties and liabilities of the
Delaware Trustee expressly set forth in this Agreement.

Section 8.14. Amendment to Certificate of Trust. If at any time required by
Section 3810 of the Statutory Trust Statute, the Trustee, the Delaware Trustee
and any other trustee of the Trust shall cause an amendment to the Certificate
of Trust to be filed with the Secretary of State in accordance with the
provisions of such Section 3810.

Section 8.15. Limitation of Liability. It is expressly understood and agreed by
the parties hereto that (a) each of the representations, undertakings and
agreements herein made on the part of the Trust is made and intended not as
personal representations, undertakings and agreements by the Trustee but is made
and intended for the purpose of binding only the Trust and (b) under no
circumstances shall the Trustee be personally liable for the payment of any
indebtedness or expenses of the Trust or be liable for the breach or failure of
any obligation, representation, warranty or covenant made or undertaken by the
Trust under this Agreement.

                                   ARTICLE IX

                                   Termination

Section 9.01.     Termination Upon Purchase by the Certificate Administrator of
the Underlying Certificates.

         (a) Except as otherwise set forth in this Article IX, including,
without limitation, the obligation of the Certificate Administrator to make
payments to Certificateholders as hereafter set forth, the Trust and the
respective obligations and responsibilities of the Company, the Certificate
Administrator, the Trustee and the Delaware Trustee created hereby shall
terminate in accordance with Section 3808 of the Statutory Trust Statute upon
(i) the purchase by the Certificate Administrator pursuant to the following
paragraph of this Section 9.01(a) of the Underlying Certificates and all other
property included in any REMIC formed under this Agreement at a price equal to
the sum of (x) 100% of the aggregate outstanding Class Principal Balance of the
Underlying Certificates (after giving effect to the distribution of principal


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<PAGE>

and allocation of Realized Losses to the Underlying Certificates on such
Distribution Date) and (y) the appraised fair market value as of the effective
date of the termination of the Trust of all other property included in any REMIC
formed under this Agreement, any such appraisal to be conducted by an appraiser
mutually agreed upon by the Certificate Administrator and the Trustee, or (ii)
the final payment (or any advance with respect thereto) of the Underlying
Certificates, and the payment to the Certificateholders and the Certificate
Insurer of all amounts required to be paid to them hereunder; provided, however,
that in no event shall the Trust continue beyond the expiration of 21 years from
the death of the survivor of the issue of Joseph P. Kennedy, the late ambassador
of the United States to the Court of St. James, living on the date hereof.

         On any Distribution Date after the first date on which the aggregate
Class Principal Balance of the Underlying Certificates is less than the Clean-Up
Call Percentage of the aggregate Class Principal Balance of the Underlying
Certificates as of the Closing Date, the Certificate Administrator may purchase
the Underlying Certificates (after giving effect to the distributions and the
allocation of Realized Losses to the Underlying Certificates on such
Distribution Date), and all other property included in any REMIC formed under
this Agreement at the price stated in clause (i) of the preceding paragraph;
provided, that the Certificate Administrator may not so purchase the Underlying
Certificates and all other property included in any REMIC formed under this
Agreement if the price stated in clause (i) of the preceding paragraph exceeds
the fair market value, determined in accordance with prudent industry practices,
of all Underlying Certificates and all other property included in any REMIC
formed under this Agreement. If such right is exercised, the Certificate
Administrator shall provide to the Trustee and to the Certificate Insurer (and
to the Company, if the Company is no longer acting as Certificate Administrator)
the written certification of an officer of the Certificate Administrator (which
certification shall include a statement to the effect that all amounts required
to be paid in order to purchase the Underlying Certificates have been deposited
in the Certificate Account) and the Trustee on behalf of the Trust shall
promptly execute all instruments as may be necessary to release and assign to
the Certificate Administrator the Underlying Certificates to the Trust.

         In no event shall the Certificate Administrator be required to expend
any amounts other than those described in the first paragraph of this Section
9.01(a) in order to terminate the Trust or purchase the Underlying Certificates
under this Section 9.01, and in no event shall the Company be required to expend
any amounts in connection with such termination or purchase.

         (b) Notice of any termination, specifying the date upon which the
Certificateholders may surrender their Certificates to the Trustee for payment
and cancellation, shall be given promptly by letter from the Trustee to
Certificateholders mailed not less than 30 days prior to such final
distribution, specifying (i) the date upon which final payment of the
Certificates will be made upon presentation and surrender of Certificates at the
office of the Certificate Registrar therein designated (the "Termination Date"),
(ii) the amount of such final payment (the "Termination Payment") and (iii) that
the Record Date otherwise applicable to the Distribution Date upon which the
Termination Date occurs is not applicable, payments being made only upon
presentation and surrender of the Certificates at the office of the Certificate
Registrar therein specified. Upon any such notice, the Certificate Account shall
terminate subject to the Certificate Administrator's obligation to hold all
amounts payable to Certificateholders in trust without interest pending such
payment.



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<PAGE>

         In the event that all of the Certificateholders shall not surrender
their Certificates for cancellation within six months after the Termination
Date, the Certificate Administrator shall give a second written notice to the
remaining Certificateholders to surrender their Certificates for cancellation
and receive the Termination Payment with respect thereto. If within one year
after the second notice all the Certificates shall not have been surrendered for
cancellation, the Certificate Administrator may take appropriate steps to
contact the remaining Certificateholders concerning surrender of their
Certificates, and the cost thereof shall be paid out of the funds and other
assets which remain in trust hereunder.

         Upon the completion of winding up of the Trust, including the payment
or the making reasonable provision for payment of all obligations of the Trust
in accordance with Section 3808(e) of the Statutory Trust Statute, the Delaware
Trustee shall prepare, the Trustee, the Delaware Trustee and any other trustee
hereunder shall sign, and the Delaware Trustee (upon the Trustee's consent
acting at the direction of the Certificate Administrator) shall file, a
certificate of cancellation with the Secretary of State in accordance with
Section 3810 of the Statutory Trust Statute, at which time the Trust and this
Agreement shall terminate. The Certificate Administrator shall act as the
liquidator of the Trust and shall be responsible for taking all actions in
connection with winding up the Trust, in accordance with the requirements of
this Agreement (including this Section 9.01 and Section 9.02) and applicable
law.

Section 9.02.     Additional Termination Requirements.

         (a) In the event the Certificate Administrator exercises its purchase
option as provided in Section 9.01, REMIC I and REMIC II shall be terminated in
accordance with the following additional requirements, unless the Certificate
Administrator, at its own expense, obtains for the Trustee and the Certificate
Insurer an Opinion of Counsel to the effect that the failure of REMIC I and
REMIC II to comply with the requirements of this Section 9.02 will not (i)
result in the imposition of taxes on "prohibited transactions" of REMIC I and
REMIC II as described in Section 860F of the Code, or (ii) cause REMIC I or
REMIC II to fail to qualify as a REMIC at any time that any Certificates are
outstanding:

         (i) Within 90 days prior to the final Distribution Date set forth in
the notice given by the Trustee under Section 9.01, the Tax Matters Person shall
prepare the documentation required and the Tax Matters Person and the Trustee
shall adopt a plan of complete liquidation on behalf of REMIC I and REMIC II
meeting the requirements of a qualified liquidation under Section 860F of the
Code and any regulations thereunder, as evidenced by an Opinion of Counsel
obtained at the expense of the Certificate Administrator, on behalf of REMIC I
and REMIC II; and

         (ii) At or after the time of adoption of such a plan of complete
liquidation and at or prior to the final Distribution Date, the Certificate
Administrator as agent of the Trust shall sell all of the assets of REMIC I and
REMIC II to the Certificate Administrator for cash in the amount specified in
Section 9.01.

         (b) By its acceptance of any Residual Certificate, the Holder thereof
hereby agrees to authorize the Tax Matters Person and the Trustee to adopt such
a plan of complete liquidation upon the written request of the Tax Matters


                                       77
<PAGE>

Person and the Trustee and to take such other action in connection therewith as
may be reasonably requested by the Tax Matters Person or the Trustee.

Section 9.03. Trust Irrevocable. Except as expressly provided herein, the trust
created hereby is irrevocable.

                                   ARTICLE X

                            Miscellaneous Provisions

Section 10.01. Amendment.

         (a) This Agreement may be amended from time to time by the Certificate
Administrator, the Company and the Trustee, without the consent of any of the
Certificateholders, but with the prior written consent of the Certificate
Insurer with respect to any amendment that adversely affects the interests of
the Certificate Insurer or any of the Holders of the Insured Certificates:

         (i) to cure any ambiguity;

         (ii) to correct or supplement any provision herein which may be
defective or inconsistent with any other provisions herein;

         (iii) to comply with any requirements imposed by the Code or any
regulations thereunder;

         (iv) to correct the description of any property at any time included in
REMIC I or REMIC II, or to assure the conveyance to the Trust of any property
included in REMIC I or REMIC II;

         (v) pursuant to Section 5.01(c)(v); and

         (vi) to add any provision to, or amend any provision in, this
Agreement, provided that such amendment or addition does not adversely affect in
any material respect the interests of any Certificateholder;

provided, however, that any such amendment which modifies the rights or
obligations of the Delaware Trustee hereunder shall require the consent of the
Delaware Trustee. No such amendment (other than one entered into pursuant to
clause (iii) of the preceding sentence) shall change the powers of the
Certificate Administrator. Prior to entering into any amendment (other than one
entered into pursuant to clause (iii) of the second preceding sentence) without
the consent of Certificateholders pursuant to this paragraph, the Trustee shall
require an Opinion of Counsel addressed to the Trust and the Trustee to the
effect that such amendment is permitted under this Agreement and has no material
adverse effect on the interests of the Certificateholders; provided, however,
that no such Opinion of Counsel shall be required if the Company obtains a
letter from each Rating Agency stating that the amendment would not result in
the downgrading or withdrawal of the respective ratings then assigned to the
Certificates (determined without regard to the Certificate Insurance Policy).
Prior to entering into any amendment pursuant to clause (iii) of the third


                                       78
<PAGE>

preceding sentence without the consent of Certificateholders pursuant to this
paragraph, the Trustee shall require an Opinion of Counsel to the effect that
such action is necessary or helpful to comply with the requirements imposed by
the Code or any regulations thereunder and shall not cause any REMIC formed
under this Agreement to fail to qualify as such under the Code.

         (b) This Agreement may also be amended from time to time by the
Certificate Administrator, the Company and the Trustee with the consent of the
Holders of Certificates evidencing Percentage Interests aggregating not less
than 66% of REMIC II for the purpose of adding any provisions to, or changing in
any manner or eliminating any of the provisions of, this Agreement or of
modifying in any manner the rights of the Certificateholders; provided, however,
that no such amendment shall, without the consent of the Holder of each
Certificate affected thereby (i) reduce in any manner the amount of, or delay
the timing of, distributions of principal or interest required to be made
hereunder or reduce the Certificateholder's Percentage Interest, the Certificate
Interest Rate or the Termination Payment with respect to any of the
Certificates, (ii) reduce the percentage of Percentage Interests specified in
this Section 10.01 which are required to amend this Agreement, (iii) create or
permit the creation of any lien against any part of REMIC I or REMIC II, or (iv)
modify any provision in any way which would permit an earlier retirement of the
Certificates; provided, further, that any such amendment which modifies the
rights or obligations of the Delaware Trustee hereunder shall require the
consent of the Delaware Trustee.

         Promptly after the execution of any such amendment, the Trustee shall
furnish written notification of the substance of such amendment to the Delaware
Trustee and each Certificateholder. Any failure to provide such notice, or any
defect therein, shall not, however, in any way impair or affect the validity of
any such amendment.

         It shall not be necessary for the consent of Certificateholders under
this Section 10.01 to approve the particular form of any proposed amendment, but
it shall be sufficient if such consent shall approve the substance thereof. The
manner of obtaining such consents and of evidencing the authorization of the
execution thereof by Certificateholders shall be subject to such reasonable
regulations as the Trustee may prescribe.

Section 10.02.    [Reserved.]

Section 10.03. Limitation on Rights of Certificateholders. The death or
incapacity of any Certificateholder shall not operate to terminate this
Agreement or the Trust, nor entitle such Certificateholder's legal
representatives or heirs to claim an accounting or to take any action or
proceeding in any court for a partition or winding-up of the Trust, nor
otherwise affect the rights, obligations and liabilities of the parties hereto
or any of them.

         No Certificateholder shall have any right to vote or in any manner
otherwise to control the operation and management of the Trust or the
obligations of the parties hereto (except as provided in Section 5.09, Section
7.01, Section 8.01, Section 8.02, Section 8.07, Section 10.01 and this Section
10.03), nor shall anything herein set forth, or contained in the terms of the
Certificates, be construed so as to constitute the Certificateholders from time
to time as partners or members of an association; nor shall any


                                       79
<PAGE>

Certificateholder be under any liability to any third person by reason of any
action taken by the parties to this Agreement pursuant to any provision hereof.

         No Certificateholder shall have any right by virtue or by availing of
any provision of this Agreement to institute any suit, action or proceeding in
equity or at law upon or under or with respect to this Agreement, unless such
Holder previously shall have given to the Trustee a written notice of default
and of the continuance thereof, as hereinbefore provided, and unless also the
Holders of Certificates evidencing Percentage Interests aggregating not less
than 25% of REMIC II shall have made written request upon the Trustee to
institute such action, suit or proceeding in its own name as Trustee hereunder
and shall have offered to the Trustee such reasonable indemnity as it may
require against the costs, expenses and liabilities to be incurred therein or
thereby, and the Trustee, for 60 days after its receipt of such notice, request
and offer of indemnity, shall have neglected or refused to institute any such
action, suit or proceeding. However, the Trustee is under no obligation to
exercise any of the extraordinary trusts or powers vested in it by this
Agreement or to make any investigation of matters arising hereunder or to
institute, conduct or defend any litigation hereunder or in relation hereto at
the request, order or direction of any of the Certificateholders unless such
Certificateholders have offered to the Trustee reasonable security or indemnity
against the costs, expenses and liabilities which may be incurred therein or
thereby. It is understood and intended, and expressly covenanted by each
Certificateholder with every other Certificateholder and the Trustee, that no
one or more Holders of Certificates shall have any right in any manner whatever
by virtue or by availing of any provision of this Agreement to affect, disturb
or prejudice the rights of the Holders of any other of such Certificates, or to
obtain or seek to obtain priority over or preference to any other such Holder,
or to enforce any right under this Agreement, except in the manner herein
provided and for the equal, ratable and common benefit of all
Certificateholders. For the protection and enforcement of the provisions of this
Section 10.03, each and every Certificateholder and the Trustee shall be
entitled to such relief as can be given either at law or in equity.

         For so long as no Certificate Insurer Default exists (and whether or
not any payments with respect to Deficiency Amounts or Avoided Payments have
been made), the Certificate Insurer shall be deemed to be the sole Holder of all
outstanding Insured Certificates with respect to any rights hereunder (other
than the right to receive distributions on such Insured Certificates, except as
provided in Section 3.21); provided that such rights may not be used to reduce
the rights of the Holders of the Insured Certificates to receive distributions
or to otherwise impair their rights under this Agreement as further described in
the definition of "Certificateholder."

Section 10.04. Access to List of Certificateholders. The Certificate Registrar
shall furnish or cause to be furnished to the Trustee, within 30 days after
receipt of a request by the Trustee in writing, a list, in such form as the
Trustee may reasonably require, of the names and addresses of the
Certificateholders as of the most recent Record Date for payment of
distributions to such Certificateholders.

         If three or more Certificateholders (hereinafter referred to as
"applicants") apply in writing to the Trustee, and such application states that
the applicants desire to communicate with other Certificateholders with respect
to their rights under this Agreement or under the Certificates and is
accompanied by a copy of the communication which such applicants propose to
transmit, then the Trustee shall, within five Business Days after the receipt of


                                       80
<PAGE>

such list from the Certificate Registrar, afford such applicants access during
normal business hours to the most recent list of Certificateholders held by the
Trustee. If such a list is as of a date more than 90 days prior to the date of
receipt of such applicants' request, the Trustee shall promptly request from the
Certificate Registrar a current list as provided above, and shall afford such
applicants access to such list promptly upon receipt.

         Every Certificateholder, by receiving and holding the same, agrees with
the Certificate Administrator, the Trust, the Trustee and the Delaware Trustee
that none of the Certificate Administrator, the Trust, the Trustee or the
Delaware Trustee shall be held accountable by reason of the disclosure of any
such information as to the names and addresses of the Certificateholders
hereunder, regardless of the source from which such information was derived.

Section 10.05. Governing Law. This Agreement shall be construed in accordance
with the laws of the State of Delaware without giving effect to its conflict of
laws provisions and the obligations, rights and remedies of the parties
hereunder shall be determined in accordance with such laws without giving effect
to conflict of laws provisions.

Section 10.06. Notices. All demands, notices and communications hereunder shall
be in writing and shall be deemed to have been duly given if personally
delivered at or mailed by registered or certified mail to the applicable Notice
Address. Notices to the Rating Agencies shall also be deemed to have been duly
given if mailed by first class mail, postage prepaid, to the above listed
addresses of the Rating Agencies. Any notice required or permitted to be mailed
to a Certificateholder shall be given by first class mail, postage prepaid, at
the address of such Holder as shown in the Certificate Register. Any notice so
mailed within the time prescribed in this Agreement shall be conclusively
presumed to have been duly given, whether or not the Certificateholder receives
such notice.

Section 10.07. Severability of Provisions. If any one or more of the covenants,
agreements, provisions or terms of this Agreement shall be for any reason
whatsoever held invalid, then such covenants, agreements, provisions or terms
shall be deemed severable from the remaining covenants, agreements, provisions
or terms of this Agreement and shall in no way affect the validity or
enforceability of the other provisions of this Agreement or of the Certificates
or the rights of the Holders thereof.

Section 10.08. Counterpart Signatures. For the purpose of facilitating the
recordation of this Agreement as herein provided and for other purposes, this
Agreement may be executed simultaneously in any number of counterparts, each of
which counterparts shall be deemed to be an original, and such counterparts
shall constitute but one and the same instrument.

Section 10.09. Benefits of Agreement. Nothing in this Agreement or in any
Certificate, expressed or implied, shall give to any Person, other than the
parties hereto and their respective successors hereunder, any separate trustee
or co-trustee appointed under Section 8.10 and the Certificateholders (and,
solely to the extent expressly provided herein, the Certificate Insurer and the
Underwriter), any benefit or any legal or equitable right, remedy or claim under
this Agreement.

                                       81
<PAGE>

Section 10.10.    Notices and Copies to Rating Agencies.

         (a) The Trustee shall notify the Rating Agencies and the Certificate
Insurer of the occurrence of any of the following events, in the manner provided
in Section 10.06:

         (i) the occurrence of an Event of Default pursuant to Section 7.01,
subject to the provisions of Section 8.01(d); and

         (ii) the appointment of a successor Certificate Administrator pursuant
to Section 7.02;

         (b) The Certificate Administrator shall notify the Rating Agencies and
the Certificate Insurer of the occurrence of any of the following events, or in
the case of clauses (iii), (iv), (vii) and (viii) promptly upon receiving notice
thereof, in the manner provided in Section 10.06:

         (i) any amendment of this Agreement pursuant to Section 10.01;

         (ii) the appointment of a successor Trustee or successor Delaware
Trustee pursuant to Section 8.08;

         (iii) the filing of any claim under or the cancellation or modification
of any fidelity bond and errors and omissions coverage pursuant to Section 3.01
with respect to the Certificate Administrator;

         (iv) any change in the location of the Certificate Account;

         (v) the purchase of the Underlying Certificates pursuant to Section
9.01; and

         (vi) the occurrence of the final Distribution Date or the termination
of the trust pursuant to Section 9.01(a)(ii).

The Certificate Administrator shall provide copies of the statements pursuant to
Section 4.02, Section 4.05, Section 3.12, Section 3.13 or Section 3.15 or any
other statements or reports to the Rating Agencies (with a copy to the
Certificate Insurer) in such time and manner that such statements or
determinations are required to be provided to Certificateholders. With respect
to the reports described in the second paragraph of Section 4.05, the
Certificate Administrator shall provide such reports to the Rating Agencies
(with a copy to the Certificate Insurer) in respect of each Distribution Date,
without regard to whether any Certificateholder or the Trustee or the Delaware
Trustee has requested such report for such Distribution Date.

                                       82
<PAGE>



<PAGE>



         IN WITNESS WHEREOF, the Company, the Trustee and the Delaware Trustee
have caused their names to be signed hereto by their respective officers,
thereunto duly authorized, all as of the day and year first above written.

                                 WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

                                 By:/s/ Thomas G. Lehman
                                    __________________________________________
                                    Name: Thomas G. Lehmann
                                    Title: First Vice President

                                 CITIBANK, N.A.,
                                 as Trustee

                                 By: /s/ Karen Schluter
                                    __________________________________________
                                    Name: Karen Schluter
                                    Title: Vice President

                                CHRISTIANA BANK & TRUST COMPANY,
                                 as Delaware Trustee

                                 By: /s/ James M. Young
                                    __________________________________________
                                    Name: James M. Young
                                    Title: Assistant Vice President



Signature page to Amended and Restated Trust Agreement for WaMu Series 2004-RS1


<PAGE>
                         ACKNOWLEDGEMENT OF CORPORATION

STATE OF WASHINGTON                                  )
                                                     ) SS.
COUNTY OF KING                                       )


         I certify that I know or have satisfactory evidence that
Thomas G. Lehmann is the person who appeared before me, and said person
acknowledged that he signed this instrument, on oath stated that. he was
authorized to execute the instrument and acknowledged it as the
First Vice President of WASHINGTON MUTUAL MORTGAGE SECURITIES CORP., to be
the free and voluntary act of such party for the uses and purposes mentioned
therein.

Dated this 25th day of February, 2004.

                            Chrisdelda Landon
                            Notary Public in and for the State of Washington,
                            residing at Seattle
                            My commission expires:  2-26-2007


<PAGE>



                                 ACKNOWLEDGEMENT

STATE OF NEW YORK                     )
                                      ) SS.
COUNTY OF NEW YORK                    )

         On this 24th day of February 2004 before me, a Notary Public in and for
said State, personally appeared Karen Schluter, personally known to me
(or proved to me on the basis of satisfactory evidence) to be the person(s)
whose name(s) is/are subscribed to the within instrument and acknowledged to me
that he/she/they executed the same in his/her/their authorized capacit(ies), and
that by his/her/their signature(s) on the instrument the person(s), or the
entity upon behalf of which the person(s) acted, executed the instrument.

         WITNESS my hand and official seal.

         Signature Nanette Murphy

         (SEAL)Notary Public, State of New York
               No. 01MU6086415
               Qualifed in Kings County
               Commission Expires 1/21/07



<PAGE>


                                 ACKNOWLEDGEMENT

STATE OF DELAWARE                     )
                                      ) SS.
COUNTY OF NEWCASTLE                   )

         On this 23rd day of February 2004 before me, a Notary Public in and for
said State, personally appeared James M. Young, personally known to me
(or proved to me on the basis of satisfactory evidence) to be the person(s)
whose name(s) is/are subscribed to the within instrument and acknowledged to me
that he/she/they executed the same in his/her/their authorized capacit(ies), and
that by his/her/their signature(s) on the instrument the person(s), or the
entity upon behalf of which the person(s) acted, executed the instrument.

         WITNESS my hand and official seal.

         Signature Matthew C. Stepnowski

         (SEAL)Matthew C. Stepnowski
               Notary Public, State of Delaware
               Commission Expires Aug. 20, 2005

<PAGE>
                                                                       Exhibit A
                                                                CUSIP 92922F ML9

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-1

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-1 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $107,707,858.00

Class A-1 Certificate Interest Rate: 4.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-1 Principal Balance
as of the Closing Date: $107,707,858.00




                                   Cede & Co.
                                Registered Owner

                                      A-1

<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MM7

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-2

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-2 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $13,963,546.00

Class A-2 Certificate Interest Rate: 5.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-2 Principal Balance
as of the Closing Date: $13,963,546.00




                                   Cede & Co.
                                Registered Owner


                                      A-2
<PAGE>




                                                                       Exhibit A
                                                                CUSIP 92922F MN5

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-3

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1  Portion of the Class A-3 Principal Balance as of the Closing
                 Date Evidenced by this Certificate:
                 $15,000,000.00

Class A-3 Certificate Interest Rate: 5.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-3 Principal Balance
as of the Closing Date: $15,000,000.00




                                   Cede & Co.
                                Registered Owner


                                      A-3
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MP0

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-4

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-4 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $36,750,000.00

Class A-4 Certificate Interest Rate: 5.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-4 Principal Balance
as of the Closing Date: $36,750,000.00




                                   Cede & Co.
                                Registered Owner


                                      A-4
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MQ8

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-5

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

The Class A-5 Certificates will provide credit support to certain Classes of
Certificates, as described in the Trust Agreement.

Series 2004-RS1     Portion of the Class A-5 Principal Balance as of the Closing
                    Date Evidenced by this Certificate:
                    $4,587,000.00

Class A-5 Certificate Interest Rate: 5.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-5 Principal Balance
as of the Closing Date: $4,587,000.00




                                   Cede & Co.
                                Registered Owner


                                      A-5
<PAGE>




                                                                       Exhibit A
                                                                CUSIP 92922F MR6

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-6

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004. Interest is
not payable with respect to this Certificate.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1     Portion of the Class A-6 Principal Balance as of the Closing
                    Date Evidenced by this Certificate:
                    $245,454.00

Class A-6 Certificate Interest Rate: 0.000%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-6 Principal Balance
as of the Closing Date: $245,454.00




                                   Cede & Co.
                                Registered Owner


                                      A-6
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MS4

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-7

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-7 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $62,402,144.00

Class A-7 Certificate Interest Rate: 4.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-7 Principal Balance
as of the Closing Date: $62,402,144.00




                                   Cede & Co.
                                Registered Owner




                                      A-7
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MT2

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-8

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-8 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $39,960,856.00

Class A-8 Certificate Interest Rate: Variable

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-8 Principal Balance
as of the Closing Date: $39,960,856.00




                                   Cede & Co.
                                Registered Owner




                                      A-8
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MU9

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-9

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-9 Notional Amount as of the Closing Date
                Evidenced by this Certificate:
                $39,960,856.00

Class A-9 Certificate Interest Rate: Variable,
applied to the Class A-9 Notional Amount

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-9 Principal Balance
as of the Closing Date: $0.00

Class A-9 Notional Amount
as of the Closing Date: $39,960,856.00

                                   Cede & Co.
                                Registered Owner



                                      A-9
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MV7

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-10

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-10 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $9,070,472.00

Class A-10 Certificate Interest Rate: 5.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-10 Principal Balance
as of the Closing Date: $9,070,472.00




                                   Cede & Co.
                                Registered Owner


                                      A-10
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MW5

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-11

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1   Portion of the Class A-11 Principal Balance as of the Closing
                  Date Evidenced by this Certificate:
                  $30,597,000.00

Class A-11 Certificate Interest Rate: 5.500%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-11 Principal Balance
as of the Closing Date: $30,597,000.00




                                   Cede & Co.
                                Registered Owner



                                      A-11
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MX3

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-12

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004. Interest is
not payable with respect to this Certificate.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1  Portion of the Class A-12 Principal Balance as of the Closing
                 Date Evidenced by this Certificate:
                 $1,130,449.00

Class A-12 Certificate Interest Rate: 0.000%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-12 Principal Balance
as of the Closing Date: $1,130,449.00




                                   Cede & Co.
                                Registered Owner




                                      A-12
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MY1

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-13

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1  Portion of the Class A-13 Principal Balance as of the Closing
                 Date Evidenced by this Certificate:
                 $43,083,142.00

Class A-13 Certificate Interest Rate: Variable

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-13 Principal Balance
as of the Closing Date: $43,083,142.00




                                   Cede & Co.
                                Registered Owner




                                      A-13
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F MZ8

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-14

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-14 Notional Amount as of the Closing Date
                Evidenced by this Certificate:
                $43,083,142.00

Class A-14 Certificate Interest Rate: Variable,
applied to the Class A-14 Notional Amount

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-14 Principal Balance
as of the Closing Date: $0.00

Class A-14 Notional Amount
as of the Closing Date: $43,083,142.00

                                   Cede & Co.
                                Registered Owner




                                      A-14
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F NA2

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-15

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1  Portion of the Class A-15 Principal Balance as of the Closing
                 Date Evidenced by this Certificate:
                 $23,779,000.00

Class A-15 Certificate Interest Rate: 4.000%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-15 Principal Balance
as of the Closing Date: $23,779,000.00




                                   Cede & Co.
                                Registered Owner




                                      A-15
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F NB0

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-16

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-16 Notional Amount as of the Closing Date
                Evidenced by this Certificate:
                $3,242,590.00

Class A-16 Certificate Interest Rate: 5.500%,
applied to the Class A-16 Notional Amount

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-16 Principal Balance
as of the Closing Date: $0.00

Class A-16 Notional Amount
as of the Closing Date: $3,242,590.00

                                   Cede & Co.
                                Registered Owner




                                      A-16
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F NC8

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-17

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-17 Principal Balance as of the Closing
                Date Evidenced by this Certificate:
                $25,396,000.00

Class A-17 Certificate Interest Rate: 4.700%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-17 Principal Balance
as of the Closing Date: $25,396,000.00




                                   Cede & Co.
                                Registered Owner





                                      A-17
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F ND6

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-18

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-18 Notional Amount as of the Closing Date
                Evidenced by this Certificate:
                $230,872.00

Class A-18 Certificate Interest Rate: 5.500%,
applied to the Class A-18 Notional Amount

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-18 Principal Balance
as of the Closing Date: $0.00

Class A-18 Notional Amount
as of the Closing Date: $230,872.00

                                   Cede & Co.
                                Registered Owner







                                      A-18
<PAGE>



                                                                       Exhibit A
                                                                CUSIP 92922F NE4

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-19

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-19 Principal Balance as of the Closing
                Date Evidenced by this Certificate:
                $25,000.00

Class A-19 Certificate Interest Rate: 4.750%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-19 Principal Balance
as of the Closing Date: $25,000.00




                                   Cede & Co.
                                Registered Owner




                                      A-19
<PAGE>




                                                                       Exhibit A
                                                                CUSIP 92922F NF1

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                   Class A-20

Evidencing a beneficial interest in a pool of assets consisting of beneficial
interests in another pool of assets consisting of, among other things, mortgage
pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. This Certificate represents ownership of a "regular interest" in
a "real estate mortgage investment conduit," as those terms are defined in
Sections 860G and 860D, respectively, of the Internal Revenue Code of 1986, as
amended. The issue date of this Certificate is February 26, 2004.

Unless this Certificate is presented by an authorized representative of The
Depository Trust Company, a New York corporation ("DTC"), to the Company or its
agent for registration of transfer, exchange, or payment, and any Certificate
issued is registered in the name of Cede & Co. or such other name as is
requested by an authorized representative of DTC (and any payment is made to
Cede & Co. or to such other entity as is requested by an authorized
representative of DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner
hereof, Cede & Co., has an interest herein.

Series 2004-RS1 Portion of the Class A-20 Principal Balance as of the Closing
                Date Evidenced by this Certificate:
                $800,000.00

Class A-20 Certificate Interest Rate: 4.750%

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class A-20 Principal Balance
as of the Closing Date: $800,000.00




                                   Cede & Co.
                                Registered Owner



                                      A-20
<PAGE>


                                                                       Exhibit B
                                                                CUSIP 92922F NG9

                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

                                    Class R

Evidencing a Percentage Interest in certain distributions with respect to a pool
of mortgage pass-through certificates formed and administered by

                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

ANY RESALE, TRANSFER OR OTHER DISPOSITION OF THIS CERTIFICATE MAY BE MADE ONLY
IF THE PROPOSED TRANSFEREE PROVIDES A TRANSFER AFFIDAVIT TO THE COMPANY AND THE
TRUSTEE THAT (1) SUCH TRANSFEREE IS NOT EITHER (A) THE UNITED STATES, ANY STATE
OR POLITICAL SUBDIVISION THEREOF, ANY FOREIGN GOVERNMENT, ANY INTERNATIONAL
ORGANIZATION, OR ANY AGENCY OR INSTRUMENTALITY OF ANY OF THE FOREGOING, (B) ANY
ORGANIZATION (OTHER THAN A COOPERATIVE DESCRIBED IN SECTION 521 OF THE CODE)
WHICH IS EXEMPT FROM THE TAX IMPOSED BY CHAPTER 1 OF THE CODE UNLESS SUCH
ORGANIZATION IS SUBJECT TO THE TAX IMPOSED BY SECTION 511 OF THE CODE, (C) ANY
ORGANIZATION DESCRIBED IN SECTION 1381(a)(2)(C) OF THE CODE (ANY SUCH PERSON
DESCRIBED IN THE FOREGOING CLAUSES (A), (B), OR (C) BEING HEREINAFTER REFERRED
TO AS A "DISQUALIFIED ORGANIZATION"), OR (D) AN AGENT OF A DISQUALIFIED
ORGANIZATION AND (2) NO PURPOSE OF SUCH TRANSFER IS TO ENABLE THE TRANSFER TO
IMPEDE THE ASSESSMENT OR COLLECTION OF TAX. SUCH AFFIDAVIT SHALL INCLUDE CERTAIN
REPRESENTATIONS AS TO THE FINANCIAL CONDITION OF THE PROPOSED TRANSFEREE.
NOTWITHSTANDING THE REGISTRATION IN THE CERTIFICATE REGISTER OF ANY TRANSFER,
SALE OR OTHER DISPOSITION OF THIS CLASS R CERTIFICATE TO A DISQUALIFIED
ORGANIZATION OR AN AGENT OF A DISQUALIFIED ORGANIZATION, SUCH REGISTRATION SHALL
BE DEEMED TO BE OF NO LEGAL FORCE OR EFFECT WHATSOEVER AND SUCH PERSON SHALL NOT
BE DEEMED TO BE A CERTIFICATEHOLDER FOR ANY PURPOSE HEREUNDER, INCLUDING, BUT
NOT LIMITED TO, THE RECEIPT OF DISTRIBUTIONS ON THIS CERTIFICATE. EACH HOLDER OF
A CLASS R CERTIFICATE BY ACCEPTANCE OF THIS CERTIFICATE SHALL BE DEEMED TO HAVE
CONSENTED TO THE PROVISIONS OF THIS PARAGRAPH.


IN THE CASE OF ANY CLASS R CERTIFICATE PRESENTED FOR REGISTRATION IN THE NAME OF
ANY PERSON, THE TRUSTEE SHALL REQUIRE (I) AN OFFICER'S CERTIFICATE IN THE FORM
DESCRIBED IN SECTION 5.01(d) OF THE TRUST AGREEMENT AND (II) IF SO INDICATED IN
SUCH OFFICER'S CERTIFICATE, AN OPINION OF COUNSEL ACCEPTABLE TO AND IN FORM AND
SUBSTANCE SATISFACTORY TO THE TRUSTEE AND THE COMPANY TO THE EFFECT THAT THE
PURCHASE AND HOLDING OF A CLASS R CERTIFICATE ARE PERMISSIBLE UNDER APPLICABLE
LAW, WILL NOT CONSTITUTE OR RESULT IN A NON-EXEMPT PROHIBITED TRANSACTION UNDER
SECTION 406 OF THE EMPLOYEE RETIREMENT INCOME SECURITY ACT OF 1974, AS AMENDED
("ERISA"), OR SECTION 4975 OF THE CODE AND WILL NOT SUBJECT THE TRUST, THE
TRUSTEE, THE CERTIFICATE ADMINISTRATOR OR THE COMPANY TO ANY OBLIGATION OR
LIABILITY (INCLUDING OBLIGATIONS OR LIABILITIES UNDER SECTION 406 OF ERISA OR
SECTION 4975 OF THE CODE) IN ADDITION TO THOSE UNDERTAKEN IN THE TRUST
AGREEMENT, WHICH OPINION OF COUNSEL SHALL NOT BE AN EXPENSE OF THE TRUST, THE
TRUSTEE, THE CERTIFICATE ADMINISTRATOR OR THE COMPANY.


This Certificate is issued by WaMu Mortgage Pass-Through Certificates Series
2004-RS1 Trust. Solely for U.S. federal income tax purposes, this Certificate
represents "residual interests" in "real estate mortgage investment conduits,"
as those terms are defined in Sections 860G and 860D, respectively, of the
Internal Revenue Code of 1986, as amended.

Series 2004-RS1 Percentage Interest evidenced by this Class R Certificate in the
                distributions to be made with respect to the
                Class R Certificates: ___________________________%

Class R Certificate Interest Rate: 5.485%.  Additionally
the Class R Certificates are entitled to Excess
Liquidation Proceeds and the Residual Distribution
Amount as defined in the Trust Agreement.

Closing Date: February 26, 2004

First Distribution Date: March 25, 2004

Last Scheduled Distribution Date: November 25, 2033

Class R Principal Balance as of the Closing Date: $100.00

                               ------------------
                                Registered Owner

                              Certificate No. ___




                                      B-1
<PAGE>



This Certificate does not represent an obligation of or interest in Washington
Mutual Mortgage Securities Corp. or any of its affiliates. Neither this
Certificate nor the Underlying Certificates are guaranteed by any agency or
instrumentality of the United States.

This certifies that the above-named Registered Owner is the registered owner of
certain interests in (i) a pool of assets ("REMIC I") consisting of, among other
things, mortgage pass-through certificates (the "Underlying Certificates"),
formed and administered by Washington Mutual Mortgage Securities Corp. (the
"Company"), which term includes any successor entity under the Trust Agreement
referred to below, and (ii) a pool of assets ("REMIC II") consisting of
interests in REMIC I. REMIC I and REMIC II were created pursuant to an Amended
and Restated Trust Agreement, dated as of the Closing Date stated above (the
"Trust Agreement"), among the Company, Citibank, N.A., as Trustee (the
"Trustee"), and Christiana Bank & Trust Company, as Delaware Trustee, a summary
of certain of the pertinent provisions of which is set forth hereafter. To the
extent not defined herein, the capitalized terms used herein have the meanings
assigned in the Trust Agreement. Nothing herein shall be deemed inconsistent
with such meanings, and in the event of any conflict between the Trust Agreement
and the terms of this Certificate, the Trust Agreement shall control. This
Certificate is issued under and is subject to the terms, provisions and
conditions of the Trust Agreement, to which Trust Agreement the Holder of this
Certificate, by virtue of the acceptance hereof, assents and by which such
Holder is bound.

Distributions will be made, pursuant to the Trust Agreement, on the 25th day of
each month or, if such 25th day is not a Business Day, the Business Day
immediately following (the "Distribution Date"), commencing on the first
Distribution Date specified above, to the Person in whose name this Certificate
is registered at the close of business on the last day (or if such last day is
not a Business Day, the Business Day immediately preceding such last day) of the
month immediately preceding the month of such distribution (the "Record Date"),
to the extent of such Certificateholder's Percentage Interest represented by
this Certificate in the portions (if any) then distributable on the Certificates
of this Class of (i) the REMIC I Available Distribution Amount for such
Distribution Date, as specified in Section 4.01 of the Trust Agreement and (ii)
the REMIC II Available Distribution Amount for such Distribution Date, as
specified in Section 4.04 of the Trust Agreement.

Distributions on this Certificate will be made by the Trustee by wire transfer
or check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register. Notwithstanding the above, the
final distribution on this Certificate will be made after due notice by the
Trustee of the pendency of such distribution and only upon presentation and
surrender of this Certificate to the Certificate Registrar.

Reference is hereby made to the further provisions of this Certificate set forth
below, which further provisions shall for all purposes have the same effect as
if set forth at this place.

Unless the certificate of authentication hereon has been executed by or on
behalf of the Trustee, by manual signature, this Certificate shall not be
entitled to any benefit under the Trust Agreement or be valid for any purpose.



                                      B-2
<PAGE>



IN WITNESS WHEREOF, the Trust has caused this Certificate to be duly executed.

WaMu MORTGAGE PASS-THROUGH CERTIFICATES SERIES 2004-RS1 TRUST



                                By:      CITIBANK, N.A., as Trustee



                                        By:





                   (TRUSTEE'S CERTIFICATE OF AUTHENTICATION)

   This is one of the Certificates referred to in the within-mentioned Trust
Agreement.

CITIBANK, N.A.,
as Trustee



By:

Dated:



                                      B-3
<PAGE>



                   WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

This Certificate is one of a duly authorized issue of Certificates designated as
WaMu Mortgage Pass-Through Certificates of the Series and Class specified hereon
(herein called the "Certificates") and representing certain interests in REMIC I
and REMIC II.

The Certificates do not represent an obligation of, or an interest in, the
Company or any of its affiliates and are not insured or guaranteed by any
governmental agency. The Certificates are limited in right of payment to certain
collections and recoveries respecting the Underlying Certificates, all as more
specifically set forth herein and in the Trust Agreement.

As provided in the Trust Agreement, withdrawals from the Certificate Account may
be made from time to time for purposes other than distributions to
Certificateholders, such purposes including reimbursement to the Certificate
Administrator of certain expenses incurred by it.

The Trust Agreement permits, with certain exceptions therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Certificateholders under the Trust Agreement at
any time by the Company, the Certificate Administrator and the Trustee with the
consent of the Holders of the Certificates evidencing Percentage Interests
aggregating not less than 66% of REMIC II. The Trust Agreement also permits the
amendment thereof, in certain limited circumstances, without the consent of the
Holders of any of the Certificates.

As provided in the Trust Agreement and subject to certain limitations therein
set forth, the transfer of this Certificate is registrable in the Certificate
Register upon surrender of this Certificate for registration of transfer at the
offices of the Certificate Registrar or the office maintained by the Trustee in
the City and State of New York, duly endorsed by, or accompanied by an
assignment in the form below or other written instrument of transfer in form
satisfactory to the Trustee or any Authenticating Agent duly executed by, the
Holder hereof or such Holder's attorney duly authorized in writing, and
thereupon one or more new Certificates of Authorized Denominations evidencing
the same Percentage Interest set forth hereinabove will be issued to the
designated transferee or transferees.

The Certificates are issuable only as registered Certificates without coupons in
Authorized Denominations specified in the Trust Agreement. As provided in the
Trust Agreement and subject to certain limitations therein set forth,
Certificates are exchangeable for new Certificates of Authorized Denominations
of like Certificate Principal Balance or Percentage Interest, as applicable, as
requested by the Holder surrendering the same.

A reasonable service charge may be made for any such registration of transfer or
exchange, and the Trustee may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith.

The Company, the Trustee and the Certificate Registrar and any agent of the
Company, the Trustee or the Certificate Registrar may treat the Person in whose
name this Certificate is registered as the owner hereof for all purposes, and
neither the Company, the Trustee, the Certificate Registrar nor any such agent
shall be affected by notice to the contrary.

The obligations created by the Trust Agreement and the Trust created thereby
shall terminate upon (i) the later of the maturity or other liquidation
(including purchase by the Certificate Administrator) of the last Underlying
Certificate remaining in the Trust and (ii) the payment to Certificateholders of
all amounts held by the Trustee and required to be paid to them pursuant to the


                                      B-4
<PAGE>

Trust Agreement. In the event that the Company or the Certificate Administrator
purchases any Underlying Agreement pursuant to the Trust Agreement, the Trust
Agreement generally requires that the Trustee distribute to the
Certificateholders in the aggregate an amount equal to 100% of the unpaid Class
Principal Balance of such Underlying Certificate. The Trust Agreement permits,
but does not require, the Certificate Administrator to purchase from the Trust
all Underlying Certificates at the time subject thereto upon payment to the
Certificateholders of the amounts specified in the Trust Agreement. The exercise
of such right will effect early retirement of the Certificates, the Certificate
Administrator's right to purchase being subject to the aggregate Class Principal
Balance of the Underlying Certificates at the time of purchase being less than
the Clean-Up Call Percentage of the aggregate Class Principal Balance of the
Underlying Certificates as of the Closing Date.










                                      B-5
<PAGE>

                                   ASSIGNMENT



     FOR VALUE  RECEIVED  the  undersigned  hereby  sell(s)  and  assign(s)  and
transfer(s)  unto ____________________________________________________________
(Please print or typewrite name and address,  including postal
zip code of assignee.  Please insert social security or other identifying number
of assignee.)

the within WaMu Mortgage  Pass-Through  Certificate and hereby irrevocably
constitutes and appoints _____________________________________________________
Attorney to transfer said  Certificate on the  Certificate  Register,  with
full power of substitution in the premises.

Dated: ______________________ ________________________________________________
                              Signature Guaranteed

    __________________________________________________________________________
    NOTICE: The signature to this  assignment  must  correspond  with the name
            as  written  upon  the  face of the  within  instrument  in  every
            particular,  without  alteration  or  enlargement  or  any  change
            whatever.  This  Certificate  does not  represent an obligation of
            or an interest in Washington  Mutual Mortgage  Securities Corp. or
            any  of  its   affiliates.   Neither  this   Certificate  nor  the
            underlying   Mortgage  Loans  are  guaranteed  by  any  agency  or
            instrumentality of the United States.



                                      B-6

<PAGE>



                                   [Reserved]




                                      C-1
<PAGE>




                                                                       Exhibit D

                       Subgroup 2 Mortgage Loan Schedule



     Copies of the Mortgage Loan Schedule (which has been intentionally omitted
from this filing) may be obtained from Washington Mutual Mortgage Securities
Corp. or Citibank, N.A. by contacting:


         in the case of Washington Mutual Mortgage Securities Corp.,

               Laura Kelsey
               Master Servicing Department
               Washington Mutual Mortgage Securities Corp.
               75 N. Fairway Drive, VHF2A01
               Vernon Hills, IL 60061
               Telephone: (847) 393-5198
               Facsimile: (847) 549-2997

          in the case of Citibank, N.A.,

               Karen Schluter
               Citibank, N.A.
               111 Wall Street
               14th Floor, Zone 3
               New York, New York  10005
               Telephone: (212) 657-7781
               Facsimile: (212) 657-4009






                                      D-1
<PAGE>


                                                                       Exhibit E


                             SELLING AND SERVICING

                                    CONTRACT


This Selling and Servicing Contract (this "Agreement") is made and entered into
by Washington Mutual Mortgage Securities Corp. and its successors and assigns
("Washington Mutual Mortgage") and the entity identified below and its
successors and assigns (the "Company").


                                  WITNESSETH:

         WHEREAS, this Company wishes to sell first lien residential mortgage
loans to, and service first lien residential mortgage loans on behalf of,
Washington Mutual Mortgage; and

         WHEREAS, the Company has submitted a Seller Application to Washington
Mutual Mortgage and has been approved by Washington Mutual Mortgage for
participation in the Washington Mutual Mortgage Purchase Programs; and

         WHEREAS, the Company has received and reviewed the Washington Mutual
Mortgage Purchase Programs Seller Guide (the "Seller Guide"), as well as the
Washington Mutual Mortgage Servicing Guide (the "Servicing Guide" and, together
with the Seller Guide, the "Guides"), and understands each and every provision
thereof;

         NOW, THEREFORE, in consideration of the premises and of the mutual
agreements herein contained, Washington Mutual Mortgage and the Company hereby
agree as follows:

         1. Guides. The Guides, which set forth the terms and conditions under
which Washington Mutual Mortgage may elect to purchase mortgage loans from the
Company, and the Company shall service mortgage loans on behalf of Washington
Mutual Mortgage, are a supplement to this Agreement and such Guides, as may be
amended or supplemented from time to time by Washington Mutual Mortgage, are
incorporated into this Agreement in full by reference and made a part hereof as
fully as if set forth at length herein. All capitalized terms used and not
defined herein have the meanings ascribed to them in the Guides.

         2. Company's Duties. The Company shall diligently perform all duties
incident to the origination, sale and servicing of the mortgage loans subject to
this Agreement. In the performance of its servicing duties, the Company shall
exercise the same degree of care it exercises when servicing mortgage loans for
its own account, but in no event shall the Company exercise less care than a
reasonable prudent servicer would exercise under similar circumstances. In
addition, the Company shall comply with all of the provisions of the Guides and
with all other requirements and instructions of Washington Mutual Mortgage. The
Company shall perform such duties at its sole expense, except as otherwise
expressly provided in the Guides.

         3. Representations, Warranties and Covenants of the Company; Remedies
of Washington Mutual Mortgage. With respect to each mortgage loan sold by the
Company to Washington Mutual Mortgage pursuant to the terms of this Agreement,
the Company shall make all of the representations, warranties and covenants set
forth in the Guide and, in the event of the breach of any of such
representations, warranties and covenants, Washington Mutual Mortgage shall have
all of the remedies available at law or in equity, as well as all of the
remedies set forth in the Guide, including, but not limited to, repurchase and
indemnification. The representations and warranties made by the Company with


                                      E-1
<PAGE>

respect to any mortgage loan subject to this Agreement, as well as the remedies
available to Washington Mutual Mortgage upon the breach thereof, shall survive:
(a) any investigation regarding the mortgage loan conducted by Washington Mutual
Mortgage, its assignees or designees, (b) the liquidation of the mortgage loan,
(c) the purchase of the mortgage loan by Washington Mutual Mortgage, its
assignee or designee, (d) the repurchase of the mortgage loan by the Company and
(e) the termination of this Agreement.

         4. Compensation. The Company shall be compensated for its services
hereunder as specified in the Guides.

         5. No Assignment. This Agreement may not be assigned by the Company
without the prior written consent of Washington Mutual Mortgage. The Company
hereby consents to the assignment by Washington Mutual Mortgage of all or any
part of its rights and obligations under this Agreement to any affiliate
designated by Washington Mutual Mortgage. Any other transfer by Washington
Mutual Mortgage will be allowed and be effective upon written notice by
Washington Mutual Mortgage to the Company.

         6. Prior Agreements. This Agreement supersedes any prior agreements and
understandings between Washington Mutual Mortgage and the Company governing the
subject matter hereof; provided, however, the Company shall not be released from
any responsibility or liability that may have arisen under such agreements and
understanding.

         7. Effective Date of Agreement. This Agreement is not effective until
it is executed and accepted by Washington Mutual Mortgage at its home office in
Illinois.

         8. Notices. All notices, requests, demands or other communications that
are to be given under this Agreement shall be in writing, addressed to the
appropriate parties, and shall be sent by certified mail, return receipt
requested, postage prepaid, if to the Company, at the address below and, if to
Washington Mutual Mortgage, to the appropriate address or facsimile number
specified in the Guides. Any such notice, request, demand or other communication
shall be deemed effective upon receipt.

         9. Independent Contractor. At no time shall the Company represent that
it is acting as an agent, partner or joint venturer of Washington Mutual
Mortgage. The Company shall at all times act as an independent contracting
party.

         10. Amendment. This Agreement may not be amended or modified orally,
and no provision of this Agreement may be waived or amended, except in writing
signed by the party against whom enforcement is sought. Such a written waiver or
amendment must expressly reference this Agreement. However, by their terms the
Guides may be amended or supplemented by Washington Mutual Mortgage from time to
time. Any such amendment(s) to the Guides shall be in writing and be binding
upon the parties hereto on and after the effective date specified therein.

         11. Miscellaneous. This Agreement, including all documents incorporated
by reference herein, constitutes the entire understanding between the parties
hereto and supersedes all other agreements, covenants, representations,
warranties, understandings and communications between the parties, whether
written or oral, with respect to the transactions contemplated by this
Agreement. All section headings contained herein are for convenience only and
shall not be construed as part of this Agreement. Any provision of this
Agreement that is prohibited or unenforceable in any jurisdiction shall as to
such jurisdiction be ineffective to the extent of such prohibition or
unenforceability without invalidating the remaining portions hereof or affecting


                                      E-2
<PAGE>

the validity or enforceability of such provision in any other jurisdiction, and
to this end, the provisions hereof are severable. This Agreement shall be
governed by, and construed and enforced in accordance with, applicable federal
laws and laws of the State of Illinois, without reference to conflict of laws
principles. This Agreement may be executed in one or more counterparts, each of
which shall constitute an original and all of which shall constitute the same
Agreement.

         IN WITNESS WHEREOF, the parties have executed this Agreement by proper
officials duly authorized on the dates hereinafter set forth. This Agreement
shall take effect as of the date of its execution in original or facsimile
signature by a duly authorized officer of Washington Mutual Mortgage.

_______________________                 _______________________________
Name of the  Company                    Company  I.D.  Number
_______________________                 _______________________________
Type of organization                    Organized under laws of
____________________________            _____________________________________
Principal place of business:            street address, city, state, zip code
________________________________________________________
Typed name and title of the Company's authorized officer
_______________________________________________________  _______________________
Signature of the Company's authorized officer            Date

Agreed to and accepted by Washington Mutual Mortgage Securities Corp.
________________________________________________________________________________
Typed name and title of authorized representative
_______________________________________________________   ______________________
Signature of authorized representative                    Date



                                      E-3



<PAGE>



                                                                       Exhibit F


                                   [Reserved]











                                      F-1

<PAGE>



                                                                       Exhibit G


                                   [Reserved]


















                                      G-1
<PAGE>



                                                                       Exhibit H


                   FORM OF ADDITIONAL MATTER INCORPORATED INTO
       THE FORM OF THE CERTIFICATES (OTHER THAN THE CLASS R CERTIFICATES)

This Certificate does not represent an obligation of or interest in Washington
Mutual Mortgage Securities Corp. or any of its affiliates. Neither this
Certificate nor the Underlying Certificates are guaranteed by any agency or
instrumentality of the United States.

This certifies that the above-named Registered Owner is the registered owner of
certain interests in a pool of assets ("REMIC II") consisting of interests in
another pool of assets ("REMIC I") consisting of, among other things, mortgage
pass-through certificates (the "Underlying Certificates"), formed and
administered by Washington Mutual Mortgage Securities Corp. (the "Company"),
which term includes any successor entity under the Trust Agreement referred to
below. REMIC I and REMIC II were created pursuant to a Amended and Restated
Trust Agreement, dated as of the Closing Date stated above (the "Trust
Agreement"), among the Company, Citibank, N.A., as Trustee (the "Trustee"), and
Christiana Bank & Trust Company, as Delaware Trustee, a summary of certain of
the pertinent provisions of which is set forth hereafter. To the extent not
defined herein, the capitalized terms used herein have the meanings assigned in
the Trust Agreement. Nothing herein shall be deemed inconsistent with such
meanings, and in the event of any conflict between the Trust Agreement and the
terms of this Certificate, the Trust Agreement shall control. This Certificate
is issued under and is subject to the terms, provisions and conditions of the
Trust Agreement, to which Trust Agreement the Holder of this Certificate, by
virtue of the acceptance hereof, assents and by which such Holder is bound.

Distributions will be made, pursuant to the Trust Agreement, on the 25th day of
each month or, if such 25th day is not a Business Day, the Business Day
immediately following (the "Distribution Date"), commencing on the first
Distribution Date specified above, to the Person in whose name this Certificate
is registered at the close of business on the last day (or if such last day is
not a Business Day, the Business Day immediately preceding such last day) of the
month immediately preceding the month of such distribution (the "Record Date"),
to the extent of such Certificateholder's Percentage Interest represented by
this Certificate in the portion of the REMIC II Available Distribution Amount
for such Distribution Date then distributable on the Certificates of this Class,
as specified in Section 4.04 of the Trust Agreement.

Distributions on this Certificate will be made by the Trustee by wire transfer
or check mailed to the address of the Person entitled thereto, as such name and
address shall appear on the Certificate Register. Notwithstanding the above, the
final distribution on this Certificate will be made after due notice by the
Trustee of the pendency of such distribution and only upon presentation and
surrender of this Certificate to the Certificate Registrar.

Reference is hereby made to the further provisions of this Certificate set forth
below, which further provisions shall for all purposes have the same effect as
if set forth at this place.

Unless the certificate of authentication hereon has been executed by or on
behalf of the Trustee, by manual signature, this Certificate shall not be
entitled to any benefit under the Trust Agreement or be valid for any purpose.




                                      H-1
<PAGE>



 IN WITNESS WHEREOF, the Trust has caused this Certificate to be duly executed.

                WaMu MORTGAGE PASS-THROUGH CERTIFICATES
                SERIES 2004-RS1 TRUST




                By:   CITIBANK, N.A., as Trustee



                      By:_____________________________________________





                    (TRUSTEE'S CERTIFICATE OF AUTHENTICATION)

     This is one of the Certificates referred to in the within-mentioned Pooling
Agreement.

CITIBANK, N.A.,
as Trustee



By:_____________________________

Dated:__________________________


                                      H-2
<PAGE>



                  WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
                     WaMu MORTGAGE PASS-THROUGH CERTIFICATE

This Certificate is one of a duly authorized issue of Certificates designated as
WaMu Mortgage Pass-Through Certificates of the Series and Class specified hereon
(herein called the "Certificates") and representing certain interests in REMIC
II.

The Certificates do not represent an obligation of, or an interest in, the
Company or any of its affiliates and are not insured or guaranteed by any
governmental agency. The Certificates are limited in right of payment to certain
collections and recoveries respecting the Underlying Certificates, all as more
specifically set forth herein and in the Trust Agreement.

As provided in the Trust Agreement, withdrawals from the Certificate Account may
be made from time to time for purposes other than distributions to
Certificateholders, such purposes including reimbursement to the Certificate
Administrator of certain expenses incurred by it.

The Trust Agreement permits, with certain exceptions therein provided, the
amendment thereof and the modification of the rights and obligations of the
Company and the rights of the Certificateholders under the Trust Agreement at
any time by the Company, the Certificate Administrator and the Trustee with the
consent of the Holders of the Certificates evidencing Percentage Interests
aggregating not less than 66% of REMIC II. Any such consent by the Holder of
this Certificate shall be conclusive and binding on such Holder and upon all
future Holders of this Certificate and of any Certificate issued upon the
transfer hereof or in exchange herefor or in lieu hereof whether or not notation
of such consent is made upon this Certificate. The Trust Agreement also permits
the amendment thereof, in certain limited circumstances, without the consent of
the Holders of any of the Certificates.

As provided in the Trust Agreement and subject to certain limitations therein
set forth, the transfer of this Certificate is registrable in the Certificate
Register upon surrender of this Certificate for registration of transfer at the
offices of the Certificate Registrar or the office maintained by the Trustee in
the City and State of New York, duly endorsed by, or accompanied by an
assignment in the form below or other written instrument of transfer in form
satisfactory to the Trustee or any Authenticating Agent duly executed by, the
Holder hereof or such Holder's attorney duly authorized in writing, and
thereupon one or more new Certificates of Authorized Denominations evidencing
the same Percentage Interest set forth hereinabove will be issued to the
designated transferee or transferees.

The Certificates are issuable only as registered Certificates without coupons in
Authorized Denominations specified in the Trust Agreement. As provided in the
Trust Agreement and subject to certain limitations therein set forth,
Certificates are exchangeable for new Certificates of Authorized Denominations
of like Certificate Principal Balance or Percentage Interest, as applicable, as
requested by the Holder surrendering the same.

A reasonable service charge may be made for any such registration of transfer or
exchange, and the Trustee may require payment of a sum sufficient to cover any
tax or other governmental charge payable in connection therewith.

The Company, the Trustee and the Certificate Registrar and any agent of the
Company, the Trustee or the Certificate Registrar may treat the Person in whose
name this Certificate is registered as the owner hereof for all purposes, and
neither the Company, the Trustee, the Certificate Registrar nor any such agent
shall be affected by notice to the contrary.

                                      H-3
<PAGE>

[to be used only in the case of the Insured Certificates:] [Each Holder of this
Certificate hereby agrees for the benefit of the Certificate Insurer that, to
the extent the Certificate Insurer makes Insured Payments, either directly or
indirectly (as by paying through the Trustee), to the Holders of the Insured
Certificates, the Certificate Insurer will be subrogated to the rights of such
Holder to the extent of such payments.]

The obligations created by the Trust Agreement and the Trust created thereby
shall terminate upon (i) the later of the maturity or other liquidation
(including purchase by the Certificate Administrator) of the last Underlying
Certificate remaining in the Trust and (ii) the payment to Certificateholders of
all amounts held by the Trustee and required to be paid to them pursuant to the
Trust Agreement. In the event that the Company or the Certificate Administrator
purchases any Underlying Certificate pursuant to the Trust Agreement, the Trust
Agreement generally requires that the Trustee distribute to the
Certificateholders in the aggregate an amount equal to 100% of the unpaid Class
Principal Balance of such Underlying Certificate. The Trust Agreement permits,
but does not require, the Certificate Administrator to purchase from the Trust
all Underlying Certificates at the time subject thereto upon payment to the
Certificateholders of the amounts specified in the Trust Agreement. The exercise
of such right will effect early retirement of the Certificates, the Certificate
Administrator's right to purchase being subject to the aggregate Class Principal
Balance of the Underlying Certificates at the time of purchase being less than
the Clean-Up Call Percentage of the aggregate Class Principal Balance of the
Underlying Certificates as of the Closing Date.







                                      H-4
<PAGE>


     FOR VALUE  RECEIVED  the  undersigned  hereby  sell(s)  and  assign(s)  and
transfer(s)  unto ____________________________________________________________
(Please print or typewrite name and address,  including postal
zip code of assignee.  Please insert social security or other identifying number
of assignee.)

the within WaMu Mortgage  Pass-Through  Certificate and hereby irrevocably
constitutes and appoints _____________________________________________________
Attorney to transfer said  Certificate on the  Certificate  Register,  with
full power of substitution in the premises.

Dated: ______________________ ________________________________________
                              Signature Guaranteed

    __________________________________________________________________________
    NOTICE: The signature to this  assignment  must  correspond  with the name
            as  written  upon  the  face of the  within  instrument  in  every
            particular,  without  alteration  or  enlargement  or  any  change
            whatever.  This  Certificate  does not  represent an obligation of
            or an interest in Washington  Mutual Mortgage  Securities Corp. or
            any  of  its   affiliates.   Neither  this   Certificate  nor  the
            underlying   Mortgage  Loans  are  guaranteed  by  any  agency  or
            instrumentality of the United States.




                                      H-5

<PAGE>


                                                                       Exhibit I


                             TRANSFEROR CERTIFICATE

                                     [Date]

Citibank, N.A., as Trustee
111 Wall Street, 14th Floor, Zone 3
New York, New York 10005
Attn: Structured Finance Group, Washington Mutual 2004-RS1

Re:      Washington Mutual Mortgage Securities Corp. WaMu Mortgage Pass-Through
         Certificates, Series 2004-RS1, Class R

Ladies and Gentlemen:

This letter is delivered to you in connection with the sale from (the "Seller")
to (the "Purchaser") of $____________________ initial Certificate Principal
Balance of WaMu Mortgage Pass-Through Certificates, Series 2004-RS1, Class R
(the "Certificate"), pursuant to Section 5.01 of the Amended and Restated Trust
Agreement (the "Trust Agreement"), dated as of February 26, 2004 among
Washington Mutual Mortgage Securities Corp., as depositor and certificate
administrator (the "Company"), Citibank, N.A., as trustee (the "Trustee"), and
Christiana Bank & Trust Company, as Delaware trustee. All terms used herein and
not otherwise defined shall have the meanings set forth in the Trust Agreement.
The Seller hereby certifies, represents and warrants to, and covenants with, the
Company, the Trustee and the Trust that:

1. No purpose of the Seller relating to the sale of the Certificate by the
Seller to the Purchaser is or will be to enable the Seller to impede the
assessment or collection of tax.

2. The Seller understands that the Purchaser has delivered to the Trustee and
the Company a transferee affidavit and agreement in the form attached to the
Trust Agreement as Exhibit J. The Seller does not know or believe that any
representation contained therein is false.

3. The Seller has no actual knowledge that the proposed Transferee is not a
Permitted Transferee.

4. The Seller has no actual knowledge that the Purchaser would be unwilling or
unable to pay taxes due on its share of the taxable income attributable to the
Certificates.

5. The Seller has conducted a reasonable investigation of the financial
condition of the Purchaser and, as a result of the investigation, found that the
Purchaser has historically paid its debts as they came due, and found no
significant evidence to indicate that the Purchaser will not continue to pay its
debts as they come due in the future.


                                      I-1

<PAGE>



6. The Purchaser has represented to the Seller that, if the Certificates
constitute a noneconomic residual interest, it (i) understands that as holder of
a noneconomic residual interest it may incur tax liabilities in excess of any
cash flows generated by the interest, and (ii) intends to pay taxes associated
with its holding of the Certificates as they become due.

                                Very truly yours,

                                [Seller]

                                By:
                                         Name:
                                         Title:





                                      I-2
<PAGE>



                                                                       Exhibit J


                       TRANSFEREE AFFIDAVIT AND AGREEMENT



STATE OF          )
                  )   ss:
COUNTY OF         )



         [NAME OF OFFICER], being first duly sworn, deposes and says:

         1. That he is [Title of Officer] of [Name of Owner] (record or
beneficial owner of the Class R Certificate (the "Owner")), a [savings
institution] [corporation] duly organized and existing under the laws of [the
State of ] [the United States], on behalf of which he makes this affidavit and
agreement.

         2. That the Owner (i) is not and will not be a "disqualified
organization" as of [date of transfer] within the meaning of Section 860E(e)(5)
of the Internal Revenue Code of 1986, as amended (the "Code") and will endeavor
to remain other than a disqualified organization for so long as it retains its
ownership interest in the Class R Certificates, and (ii) is acquiring the Class
R Certificates for its own account or for the account of another Owner from
which it has received an affidavit and agreement in substantially the same form
as this affidavit and agreement. (For this purpose, a disqualified organization"
means the United States, any state or political subdivision thereof, or any
agency or instrumentality of any of the foregoing (other than an instrumentality
all of the activities of which are subject to tax and, except for the Federal
Home Loan Mortgage Corporation, a majority of whose board of directors is not
selected by any such governmental entity), or any foreign government or
international organization, or any agency or instrumentality of such foreign
government or organization, any rural electric or telephone cooperative, or any
organization (other than certain farmers' cooperatives) that is generally exempt
from federal income tax unless such organization is subject to the tax on
unrelated business taxable income).

         3. That the Owner is aware (i) of the tax that would be imposed on
transfers of the Class R Certificates after March 31, 1988; (ii) that such tax
would be on the transferor, or, if such transfer is through an agent (which
person includes a broker, nominee or middle-man) for a disqualified
organization, on the agent; (iii) that the person otherwise liable for the tax
shall be relieved of liability for the tax if the transferee furnishes to such
person an affidavit that the transferee is not a disqualified organization and,
at the time of transfer, such person does not have actual knowledge that the
affidavit is false; and (iv) that the Class R Certificates may be a "noneconomic
residual interest" within the meaning of Treasury regulations promulgated
pursuant to the Code and that the transferor of a noneconomic residual interest
will remain liable for any taxes due with respect to the income on such residual
interest, if a significant purpose of the transfer was to enable the transferor
to impede the assessment or collection of tax.

         4. That the Owner is aware of the tax imposed on a "pass-through
entity" holding the Class R Certificates if at any time during the taxable year
of the pass-through entity a disqualified organization is the record holder of
an interest in such entity. (For this purpose, a "pass through entity" includes
a regulated investment company, a real estate investment trust or common trust
fund, a partnership, trust or estate, and certain cooperatives.)

                                      J-1
<PAGE>

         5. That the Owner is aware that the Trustee will not register the
Transfer of the Class R Certificates unless the transferee, or the transferees'
agent, delivers to it an affidavit and agreement, among other things, in
substantially the same form as this affidavit and agreement. The Owner expressly
agrees that it will not consummate any such transfer if it knows or believes
that any of the representations contained in such affidavit and agreement are
false.

         6. That the Owner has reviewed the restrictions set forth on the face
of the Class R Certificates and the provisions of Section 5.01 of the Trust
Agreement under which the Class R Certificates were issued (in particular,
clauses (iii)(A) and (iii)(B) of Section 5.01(c) which authorize the Trustee to
deliver payments to a person other than the Owner and negotiate a mandatory sale
by the Trustee in the event the Owner holds such Certificates in violation of
Section 5.01). The Owner expressly agrees to be bound by and to comply with such
restrictions and provisions.

         7. That the Owner consents to any additional restrictions or
arrangements that shall be deemed necessary upon advice of counsel to constitute
a reasonable arrangement to ensure that the Class R Certificates will only be
owned, directly or indirectly, by an Owner that is not a disqualified
organization.

         8. The Owner's Taxpayer Identification Number is .

         9. That no purpose of the Owner relating to the purchase of the Class R
Certificates by the Owner is or will be to enable the transferor to impede the
assessment or collection of tax, and that in making this representation, the
Owner warrants that the Owner is familiar with Treasury Regulation 1.860E-1(c)
and with the preamble to the adoption of amendments to that regulation as of
July 19, 2002, attached hereto as Exhibit 1.

         10. That the Owner anticipates that it will, so long as it holds the
Class R Certificates, have sufficient assets to pay any taxes owed by the holder
of such Certificates, and hereby represents to and for the benefit of the person
from whom it acquired the Class R Certificates that the Owner intends to pay
taxes associated with holding such Certificates as they become due, fully
understanding that it may incur tax liabilities in excess of any cash flows
generated by the Class R Certificates. That the Owner has provided financial
statements or other financial information requested by the transferor in
connection with the transfer of the Class R Certificates to permit the
transferor to assess the financial capability of the Owner to pay such taxes.

         11. That the Owner has no present knowledge or expectation that it will
be unable to pay any United States taxes owed by it so long as any of the Class
R Certificates remain outstanding.

         12. That the Owner has no present knowledge or expectation that it will
become insolvent or subject to a bankruptcy proceeding for so long as any of the
Class R Certificates remain outstanding.

         13. That the Owner is familiar with Treasury Regulation 1.860E-1(c) and
with the preamble to the adoption of amendments to that regulation as of July
19, 2002, attached hereto as Exhibit 1, and that no purpose of the Owner
relating to any sale of the Class R Certificates by the Owner will be to impede
the assessment or collection of tax.

         14. The Owner is a citizen or resident of the United States, a
corporation, partnership or other entity treated as a partnership or corporation
for U.S. federal income tax purposes created or organized in, or under the laws
of, the United States or any state thereof or the District of Columbia, or an
estate or trust whose income from sources without the United States is
includible in gross income for United States federal income tax purposes
regardless of its connection with the conduct of a trade or business within the
United States.

                                      J-2
<PAGE>

         15. The Owner hereby agrees that it will not cause income from the
Class R Certificates to be attributable to a foreign permanent establishment or
fixed base (within the meaning of an applicable income tax treaty) of the Owner
or another United States taxpayer.

         16. The Owner hereby agrees to cooperate with the Company and to take
any action required of it by the Code or Treasury regulations thereunder
(whether now or hereafter promulgated) in order to create or maintain the REMIC
status of REMIC I and REMIC II (the "REMICs").

         17. The Owner hereby agrees that it will not take any action that could
endanger the REMIC status of the REMICs or result in the imposition of tax on
the REMICs unless counsel for, or acceptable to, the Company has provided an
opinion that such action will not result in the loss of such REMIC status or the
imposition of such tax, as applicable.

         18. The Owner as transferee of the Class R Certificates has represented
to the transferor that, if the Class R Certificates constitute a noneconomic
residual interest, the Owner (i) understands that as holder of a noneconomic
residual interest it may incur tax liabilities in excess of any cash flows
generated by the interest, and (ii) intends to pay taxes associated with its
holding of the Class R Certificates as they become due.

         19. That the Owner satisfies the condition in the paragraph marked
below [mark one paragraph only]:

         ___ The Owner is not an employee benefit or other plan subject to the
prohibited transaction provisions of the Employee Retirement Income Security Act
of 1974, as amended, or Section 4975 of the Internal Revenue Code of 1986, as
amended (a "Plan"), or any other person (including an investment manager, a
named fiduciary or a trustee of any Plan) acting, directly or indirectly, on
behalf of, or purchasing the Class R Certificates with "plan assets" of, any
Plan within the meaning of the Department of Labor ("DOL") regulation at 29
C.F.R. Section 2510.3-101.

         ___ The Owner has delivered a Benefit Plan Opinion (as defined in
Section 1.01 of the Trust Agreement under which the Class R Certificates were
issued).

         IN WITNESS WHEREOF, the Owner has caused this instrument to be executed
on its behalf, pursuant to the authority of its Board of Directors, by its
[Title of Officer] and its corporate seal to be hereunto attached, attested by
its [Assistant] Secretary, this day of , 20 __ .

                                [Name of Owner]

                                By:
                                         [Name of Officer]
                                         [Title of Officer]

[Corporate Seal]

ATTEST:





                                      J-3
<PAGE>

[Assistant] Secretary

         Personally appeared before me the above-named [Name of Officer], known
or proved to me to be the same person who executed the foregoing instrument and
to be the [Title of Officer] of the Owner, and Acknowledged to me that he
executed the same as his free act and deed and the free act and deed of the
Owner.

Subscribed and sworn before me this ___ day of __________________, 20__.





                                NOTARY PUBLIC

                                COUNTY OF
                                STATE OF
                                My Commission expires the ___ day
                                of ______________, 20__







                                      J-4
<PAGE>

                                               Exhibit 1 to Transferee Affidavit


DEPARTMENT OF THE TREASURY
Internal Revenue Service
26 CFR Parts 1 and 602
[TD 9004]
RIN 1545-AW98

Real Estate Mortgage Investment Conduits

AGENCY: Internal Revenue Service (IRS), Treasury.

ACTION: Final regulations.

-----------------------------------------------------------------------

SUMMARY: This document contains final regulations relating to safe harbor
transfers of noneconomic residual interests in real estate mortgage investment
conduits (REMICs). The final regulations provide additional limitations on the
circumstances under which transferors may claim safe harbor treatment.

DATES:   Effective Date: These regulations are effective July 19, 2002.
Applicability Date: For dates of applicability, see Sec. 1.860E-
(1)(c)(10).

FOR FURTHER INFORMATION CONTACT: Courtney Shepardson at (202) 622-3940
(not a toll-free number).

SUPPLEMENTARY INFORMATION:

Paperwork Reduction Act

The collection of information in this final rule has been reviewed and, pending
receipt and evaluation of public comments, approved by the Office of Management
and Budget (OMB) under 44 U.S.C. 3507 and assigned control number 1545-1675. The
collection of information in this regulation is in Sec. 1.860E-1(c)(5)(ii). This
information is required to enable the IRS to verify that a taxpayer is complying
with the conditions of this regulation. The collection of information is
mandatory and is required. Otherwise, the taxpayer will not receive the benefit
of safe harbor treatment as provided in the regulation. The likely respondents
are businesses and other for-profit institutions.

Comments on the collection of information should be sent to the Office of
Management and Budget, Attn: Desk Officer for the Department of the Treasury,
Office of Information and Regulatory Affairs, Washington, DC, 20503, with copies
to the Internal Revenue Service, Attn: IRS Reports Clearance Officer,
W:CAR:MP:FP:S, Washington, DC 20224. Comments on the collection of information
should be received by September 17, 2002. Comments are specifically requested
concerning:

Whether the collection of information is necessary for the proper performance of
the functions of the Internal Revenue Service, including whether the information
will have practical utility;

                                      J-1-1
<PAGE>

The accuracy of the estimated burden associated with the collection
of information (see below);

How the quality, utility, and clarity of the information to be collected may be
enhanced;

How the burden of complying with the collection of information may be minimized,
including through the application of automated collection techniques or other
forms of information technology; and

Estimates of capital or start-up costs and costs of operation, maintenance, and
purchase of service to provide information.

An agency may not conduct or sponsor, and a person is not required to respond
to, a collection of information unless it displays a valid control number
assigned by the Office of Management and Budget.

The estimated total annual reporting burden is 470 hours, based on an estimated
number of respondents of 470 and an estimated average annual burden hours per
respondent of one hour.

Books or records relating to a collection of information must be retained as
long as their contents may become material in the administration of any internal
revenue law. Generally, tax returns and tax return information are confidential,
as required by 26 U.S.C. 6103.

Background

This document contains final regulations regarding the proposed amendments to 26
CFR part 1 under section 860E of the Internal Revenue Code (Code). The
regulations provide the circumstances under which a transferor of a noneconomic
REMIC residual interest meeting the investigation and representation
requirements may avail itself of the safe harbor by satisfying either the
formula test or the asset test.

Final regulations governing REMICs, issued in 1992, contain rules governing the
transfer of noneconomic REMIC residual interests. In general, a transfer of a
noneconomic residual interest is disregarded for all tax purposes if a
significant purpose of the transfer is to enable the transferor to impede the
assessment or collection of tax. A purpose to impede the assessment or
collection of tax (a wrongful purpose) exists if the transferor, at the time of
the transfer, either knew or should have known that the transferee would be
unwilling or unable to pay taxes due on its share of the REMIC's taxable income.

Under a safe harbor, the transferor of a REMIC noneconomic residual interest is
presumed not to have a wrongful purpose if two requirements are satisfied: (1)
the transferor conducts a reasonable investigation of the transferee's financial
condition (the investigation requirement); and (2) the transferor secures a
representation from the transferee to the effect that the transferee understands
the tax obligations associated with holding a residual interest and intends to
pay those taxes (the representation requirement).

The IRS and Treasury have been concerned that some transferors of noneconomic
residual interests claim they satisfy the safe harbor even in situations where
the economics of the transfer clearly indicate the transferee is unwilling or
unable to pay the tax associated with holding the interest. For this reason, on
February 7, 2000, the IRS published in the Federal Register (65 FR 5807) a
notice of proposed rulemaking (REG-100276-97; REG-122450-98) designed to clarify
the safe harbor by adding the "formula test," an economic test. The proposed
regulation provides that the safe harbor is unavailable unless the present value
of the anticipated tax liabilities associated with holding the residual interest


                                      J-1-2
<PAGE>

does not exceed the sum of: (1) The present value of any consideration given to
the transferee to acquire the interest; (2) the present value of the expected
future distributions on the interest; and (3) the present value of the
anticipated tax savings associated with holding the interest as the REMIC
generates losses.

The notice of proposed rulemaking also contained rules for FASITs. Section
1.860H-6(g) of the proposed regulations provides requirements for transfers of
FASIT ownership interests and adopts a safe harbor by reference to the safe
harbor provisions of the REMIC regulations.

In January 2001, the IRS published Rev. Proc. 2001-12 (2001-3 I.R.B. 335) to set
forth an alternative safe harbor that taxpayers could use while the IRS and the
Treasury considered comments on the proposed regulations. Under the alternative
safe harbor, if a transferor meets the investigation requirement and the
representation requirement but the transfer fails to meet the formula test, the
transferor may invoke the safe harbor if the transferee meets a two-prong test
(the asset test). A transferee generally meets the first prong of this test if,
at the time of the transfer, and in each of the two years preceding the year of
transfer, the transferee's gross assets exceed $100 million and its net assets
exceed $10 million. A transferee generally meets the second prong of this test
if it is a domestic, taxable corporation and agrees in writing not to transfer
the interest to any person other than another domestic, taxable corporation that
also satisfies the requirements of the asset test. A transferor cannot rely on
the asset test if the transferor knows, or has reason to know, that the
transferee will not comply with its written agreement to limit the restrictions
on subsequent transfers of the residual interest.

Rev. Proc. 2001-12 provides that the asset test fails to be satisfied in the
case of a transfer or assignment of a noneconomic residual interest to a foreign
branch of an otherwise eligible transferee. If such a transfer or assignment
were permitted, a corporate taxpayer might seek to claim that the provisions of
an applicable income tax treaty would resource excess inclusion income as
foreign source income, and that, as a consequence, any U.S. tax liability
attributable to the excess inclusion income could be offset by foreign tax
credits. Such a claim would impede the assessment or collection of U.S. tax on
excess inclusion income, contrary to the congressional purpose of assuring that
such income will be taxable in all events. See, e.g., sections 860E(a)(1), (b),
(e) and 860G(b) of the Code.

The Treasury and the IRS have learned that certain taxpayers transferring
noneconomic residual interests to foreign branches have attempted to rely on the
formula test to obtain safe harbor treatment in an effort to impede the
assessment or collection of U.S. tax on excess inclusion income. Accordingly,
the final regulations provide that if a noneconomic residual interest is
transferred to a foreign permanent establishment or fixed base of a U.S.
taxpayer, the transfer is not eligible for safe harbor treatment under either
the asset test or the formula test. The final regulations also require a
transferee to represent that it will not cause income from the noneconomic
residual interest to be attributable to a foreign permanent establishment or
fixed base.

Section 1.860E-1(c)(8) provides computational rules that a taxpayer may use to
qualify for safe harbor status under the formula test. Section 1.860E-1(c)(8)(i)
provides that the transferee is presumed to pay tax at a rate equal to the
highest rate of tax specified in section 11(b). Some commentators were concerned
that this presumed rate of taxation was too high because it does not take into
consideration taxpayers subject to the alternative minimum tax rate. In light of
the comments received, this provision has been amended in the final regulations
to allow certain transferees that compute their taxable income using the
alternative minimum tax rate to use the alternative minimum tax rate applicable
to corporations.

Additionally, Sec. 1.860E-1(c)(8)(iii) provides that the present values in the
formula test are to be computed using a discount rate equal to the applicable
Federal short-term rate prescribed by section 1274(d). This is a change from the
proposed regulation and Rev. Proc. 2001-12. In those publications the provision
stated that "present values are computed using a discount rate equal to the
applicable Federal rate prescribed in section 1274(d) compounded semiannually"
and that "[a] lower discount rate may be used if the transferee can demonstrate
that it regularly borrows, in the course of its trade or business, substantial
funds at such lower rate from an unrelated third party." The IRS and the
Treasury Department have learned that, based on this provision, certain
taxpayers have been attempting to use unrealistically low or zero interest rates
to satisfy the formula test, frustrating the intent of the test. Furthermore,
the Treasury Department and the IRS believe that a rule allowing for a rate
other than a rate based on an objective index would add unnecessary complexity


                                      J-1-3
<PAGE>

to the safe harbor. As a result, the rule in the proposed regulations that
permits a transferee to use a lower discount rate, if the transferee can
demonstrate that it regularly borrows substantial funds at such lower rate, is
not included in the final regulations; and the Federal short-term rate has been
substituted for the applicable Federal rate. To simplify taxpayers'
computations, the final regulations allow use of any of the published short-term
rates, provided that the present values are computed with a corresponding period
of compounding. With the exception of the provisions relating to transfers to
foreign branches, these changes generally have the proposed applicability date
of February 4, 2000, but taxpayers may choose to apply the interest rate formula
set forth in the proposed regulation and Rev. Proc. 2001-12 for transfers
occurring before August 19, 2002.

It is anticipated that when final regulations are adopted with respect to
FASITs, Sec. 1.860H-6(g) of the proposed regulations will be adopted in
substantially its present form, with the result that the final regulations
contained in this document will also govern transfers of FASIT ownership
interests with substantially the same applicability date as is contained in this
document.

Effect on Other Documents

Rev. Proc. 2001-12 (2001-3 I.R.B. 335) is obsolete for transfers of noneconomic
residual interests in REMICs occurring on or after August 19, 2002.

Special Analyses

It is hereby certified that these regulations will not have a significant
economic impact on a substantial number of small entities. This certification is
based on the fact that it is unlikely that a substantial number of small
entities will hold REMIC residual interests. Therefore, a Regulatory Flexibility
Analysis under the Regulatory Flexibility Act (5 U.S.C. chapter 6) is not
required. It has been determined that this Treasury decision is not a
significant regulatory action as defined in Executive Order 12866. Therefore, a
regulatory assessment is not required. It also has been determined that sections
553(b) and 553(d) of the Administrative Procedure Act (5 U.S.C. chapter 5) do
not apply to these regulations.

Drafting Information

The principal author of these regulations is Courtney Shepardson. However, other
personnel from the IRS and Treasury Department participated in their
development.

List of Subjects

26 CFR Part 1

Income taxes, Reporting and record keeping requirements.

26 CFR Part 602

Reporting and record keeping requirements.

Adoption of Amendments to the Regulations



                                      J-1-4
<PAGE>

Accordingly, 26 CFR parts 1 and 602 are amended as follows:

PART 1--INCOME TAXES

Paragraph 1. The authority citation for part 1 continues to read in part as
follows:

    Authority: 26 U.S.C. 7805 * * *








<PAGE>

                                                                       Exhibit K

                      FORM OF CERTIFICATE INSURANCE POLICY


                                                     1221 Avenue of the Americas
                                                        New York, New York 10020
                                                      Telephone:  (212) 478-3400
                                                    Facsimile:    (212) 478-3597

FINANCIAL GUARANTY INSURANCE POLICY

Obligor:  WaMu Mortgage Pass-Through Certificates          Policy No:  CA00859A
          Series 2004-RS1 Trust

Insured Obligation:  $15,000,000 5.50% WaMu Mortgage      Effective Date:
                     Pass-Through Certificates,           February 26, 2004
                     Series 2004-RS1,
                     Class A-3 Certificates

         XL Capital Assurance Inc. (XLCA), a New York stock insurance company,
in consideration of the payment of the premium, hereby unconditionally and
irrevocably guarantees to the Trustee for the benefit of the Owners of the
Insured Obligations, the full and complete payment by the Obligor of Scheduled
Payments in respect of the Insured Obligation, subject only to the terms of this
Policy (which includes the Endorsement attached hereto).

         XLCA will pay the Insured Amount to the Trustee upon the presentation
of a Payment Notice to XLCA (which Payment Notice shall include an irrevocable
assignment to XLCA of all rights and claims in respect of the relevant Insured
Obligation, as specified in the Payment Notice), on the later of (a) one (1)
Business Day following receipt by XLCA of a Payment Notice or (b) the Business
Day on which Scheduled Payments are due for payment. XLCA shall be subrogated to
the Owners' rights to payment on the Insured Obligations to the extent of any
payment by XLCA hereunder. The obligations of XLCA with respect to a Scheduled
Payment will be discharged to the extent funds to pay such Scheduled Payment are
deposited in the account specified in the Payment Notice, whether such funds are
properly applied by the Trustee or claimed by an Owner.

         In addition, in the event that any Scheduled Payment which has become
due for payment and which is made to an Owner by or on behalf of the Trustee is
recovered or is recoverable from the Owner pursuant to a final order of a court
of competent jurisdiction in an Insolvency Proceeding that such payment
constitutes an avoidable preference to such Owner within the meaning of any
applicable bankruptcy law, XLCA unconditionally and irrevocably guarantees
payment of the amount of such recovery (in accordance with Endorsement No. 1
hereto).

         This Policy sets forth in full the undertaking of XLCA and shall not be
cancelled or revoked by XLCA for any reason, including failure to receive
payment of any premium due hereunder or under the Insurance Agreement, and may
not be further endorsed or modified without the written consent of XLCA. The
premium on this Policy is not refundable for any reason. This Policy does not
insure against loss of any prepayment or other acceleration payment which at any
time may become due in respect of any Insured Obligation, other than at the sole
option of XLCA, nor against any risk other than Nonpayment and Avoided Payment,
including any shortfalls, if any, attributable to the liability of the Obligor
for taxes or withholding taxes if any, including interest and penalties in
respect of such liability.

         THIS POLICY IS NOT COVERED BY THE PROPERTY/CASUALTY INSURANCE SECURITY
FUND SPECIFIED IN ARTICLE 76 OF THE NEW YORK INSURANCE LAW.

         Any capitalized terms not defined herein shall have the meaning given
such terms in the Endorsement attached hereto and forming a part hereof, or in
the Insurance Agreement referenced therein. In witness whereof, XLCA has caused
this Policy to be executed as of the Effective Date.

         ____________________                      ___________________________
         Name:                                     Name:
         Title:                                    Title:


                                       K-1

<PAGE>


              Financial Guaranty Insurance Policy Endorsement No.1
                        Effective Date February 26, 2004

                         Attached to and forming part of
                Financial Guaranty Insurance Policy No. CA00859A

Obligor:              WaMu Mortgage Pass-Through Certificates Series
                      2004-RS1 Trust

Insured Obligation:   $15,000,000 5.50% WaMu Mortgage Pass-Through Certificates,
                      Series 2004-RS1, Class A-3 Certificates

Beneficiary:          Citibank, N.A., as Trustee

Capitalized terms used herein and not otherwise defined herein or in the Policy
shall have the meanings assigned to them in the Trust Agreement.

                  As used herein the term "Business Day" means any day other
than Saturday or Sunday on which commercial banking institutions in New York,
New York, are generally open for banking business.

                  As used herein the term "Insolvency Proceeding" means the
commencement, after the date hereof, of any bankruptcy, insolvency, readjustment
of debt, reorganization, marshalling of assets and liabilities or similar
proceedings by or against any Person, the commencement, after the date hereof,
of any proceedings by or against any Person for the winding up or liquidation of
its affairs, or the consent, after the date hereof, to the appointment of a
trustee, conservator, receiver or liquidator in any bankruptcy, insolvency,
readjustment of debt, reorganization, marshalling of assets and liabilities or
similar proceedings of or relating to any Person.

                  As used herein the term "Insured Amount" means, that portion
of the Scheduled Payments that shall become due for payment but shall be unpaid
by reason of Nonpayment.

                  As used herein the term "Nonpayment" means, with respect to
any Distribution Date, the failure of the Trustee to receive in full, in
accordance with the terms of the Trust Agreement that Scheduled Payment that is
due for payment with respect to such date.

                  As used herein the term "Owner" means the registered owner of
any Insured Obligation as indicated in the registration books maintained by or
on behalf of the Obligor for such purpose or, if the Insured Obligation is in
bearer form, the holder of the Insured Obligation.

                  As used herein, the term "Person" means an individual, a
partnership, a limited liability company, a joint venture, a corporation, a
trust, an unincorporated organization, and a government or any department or
agency thereof.

                  As used herein the term "Scheduled Payment" means, (i) with
respect to any Distribution Date during the Term of this Policy other than the
Last Scheduled Distribution Date, the sum of (a) the Interest Distribution
Amount for such Distribution Date, and (b) the principal portion of any Realized
Losses allocated to the Class A-3 Certificates on such Distribution Date, (ii)
on the Last Scheduled Distribution Date for the Insured Obligation, the sum of
(a) the aggregate Certificate Principal Balance of the Class A-3 Certificates,
(b) the Interest Distribution Amount for such Distribution Date and (c) the
principal portion of any Realized Losses allocated to the Class A-3 Certificates
on such Distribution Date (after giving effect to all other distributions to be
made thereon on such Distribution Date) in accordance with the original terms of
the Insured Obligations and the Trust Agreement when issued and without regard

                                      K-2

<PAGE>

to any subsequent amendment or modification of the Insured Obligations or the
Trust Agreement that has not been consented to in writing by XLCA and (iii) on
any Distribution Date after the first date on which (x) the Class Principal
Balance (as defined in the Pooling and Servicing Agreement) of the Underlying
Certificates is less than or equal to 10% of the Class Principal Balance (as
defined in the Pooling and Servicing Agreement) of the Underlying Certificates
as of the Closing Date and the Certificate Administrator purchases the
Underlying Certificates or (y) the aggregate Principal Balance of the mortgage
loans in which the Underlying Certificates represent an interest (the
"Underlying Mortgage Loans") is less than or equal to 5% of the aggregate
Principal Balance of the Underlying Mortgage Loans as of the Cut-Off Date of the
Underlying Trust and the Master Servicer purchases the Underlying Mortgage
Loans, the sum of (a) the aggregate Certificate Principal Balance of the Class
A-3 Certificates (after giving effect to all other distributions to be made
thereon on such Distribution Date), (b) the Interest Distribution Amount for
such Distribution Date and (c) the principal portion of any Realized Losses
allocated to the Class A-3 Certificates on such Distribution Date (without
duplication to any amounts distributed pursuant to clause (i) above).
Notwithstanding the foregoing, "Scheduled Payments" shall in no event include
payments which become due on an accelerated basis as a result of (a) any default
by the Obligor, (b) the occurrence of any event of default under the Trust
Agreement, (c) mandatory or optional redemption, in whole or in part (other than
Scheduled Payments pursuant to clause (iii) of the immediately preceding
paragraph), or (d) any other cause, unless XLCA elects, in its sole discretion,
to pay such amounts in whole or in part (in which event Scheduled Payments shall
include such accelerated payments as, when, and to the extent so elected by
XLCA). In the event that it does not make such election, Scheduled Payments
shall include payments due in accordance with the original scheduled terms
without regard to any acceleration. In addition, "Scheduled Payment" shall not
include, nor shall coverage be provided under the Policy in respect of, (i) any
make whole, redemption or call premium payable in respect of the Insured
Obligations, (ii) any amounts due in respect of the Insured Obligations
attributable to any increase in interest rate, penalty or other sum payable by
the Trust by reason of any default or event of default in respect of the Insured
Obligations, or by reason of any deterioration of the creditworthiness of the
Issuer or (iii) any taxes, withholding or other charge imposed by any
governmental authority due in connection with the payment of any Scheduled
Payment to any holder of an Insured Obligation.

                  As used herein the term "Term of this Policy" means the period
from and including the Effective Date to and including the first date on which
(i) all Scheduled Payments have been paid that are required to be paid by the
Obligor under the Indenture; (ii) the 91 day period during which any Scheduled
Payment could have been avoided in whole or in part as a preference payment
under applicable bankruptcy, insolvency, receivership or similar law has
expired, and (iii) if any proceedings requisite to avoidance as a preference
payment have been commenced prior to the occurrence of (i) and (ii) above, a
final and nonappealable order in resolution of each such proceeding has been
entered provided, further, that if the Owners are required to return any Avoided
Payment (as defined below) as a result of such insolvency proceeding, then the
Term of the Policy shall terminate on the date on which XLCA has made all
payments required to be made under the terms of this Policy in respect of all
such Avoided Payments.

                  "Relief Act Shortfalls": For any Distribution Date and for any
Mortgage Loan with respect to which the Servicemembers Civil Relief Act, or any


                                      K-3
<PAGE>

comparable state legislation (collectively, the "Relief Act"), limits the amount
of interest payable by the related Mortgagor, an amount equal to one month's
interest on such Mortgage Loan at an annual interest rate equal to the excess,
if any, of (i) the annual interest rate otherwise payable by the Mortgagor on
the related Due Date under the terms of the related Mortgage Note over (ii) the
annual interest rate payable by the Mortgagor on the related Due Date by
application of the Relief Act.

                  "Certificate Principal Balance": For each Certificate of any
Class, the portion of the related Class Principal Balance, if any, represented
by such Certificate.

                  "Interest Distribution Amount": For any Distribution Date and
the Class A-3 Certificates, the amount of interest accrued during the Prior
Period, at the related Certificate Interest Rate for such Class for such
Distribution Date, on the related Class Principal Balance immediately before
such Distribution Date, reduced by Uncompensated Interest Shortfall and the
interest portion of Realized Losses allocated to such Class pursuant to the
definition of "Uncompensated Interest Shortfall" and "Realized Loss,"
respectively. The computation of interest accrued shall be made on the basis of
a 360 -day year of twelve 30 day months.

                  "Distribution Date": With respect to distributions on the
Certificates, the 25th day (or, if such 25th day is not a Business Day, the
Business Day immediately succeeding such 25th day) of each month, with the first
such date being March 25, 2004.

                  "Last Scheduled Distribution Date": November 25, 2033, or on
the next succeeding Business Day.

                  "Realized Loss": For any Distribution Date, the amount
allocated to the Underlying Certificates pursuant to the definition of "Realized
Loss" in the Pooling and Servicing Agreement.

                  "Trust Agreement": The Amended and Restated Trust Agreement,
dated as of February 26, 2004 by and among Washington Mutual Mortgage Securities
Corp., as depositor and certificate administrator, Citibank, N.A., as trustee
and Christiana Bank & Trust Company, as Delaware trustee.

                  To make a claim under the Policy, the Trustee shall deliver to
XLCA a Payment Notice in the form of Exhibit A hereto (a "Payment Notice"),
appropriately completed and executed by the Trustee. A Payment Notice under this
Policy may be presented to XLCA by (i) delivery of the original Payment Notice
to XLCA at its address set forth below, or (ii) facsimile transmission of the
original Payment Notice to XLCA at its facsimile number set forth below. If
presentation is made by facsimile transmission, the Trustee shall (x)
simultaneously confirm transmission by telephone to XLCA at its telephone number
set forth below, and (y) as soon as reasonably practicable, deliver the original
Payment Notice to XLCA at its address set forth below. Any Payment Notice
received by XLCA after 10:00 a.m., New York City time, on a Business Day, or on
any day that is not a Business Day, will be deemed to be received by XLCA at
9:00 a.m., New York City time, on the next succeeding Business Day. XLCA shall
make payments due in respect of Insured Amounts no later than 2:00 p.m. New York
City time to the Trustee upon the presentation of a Payment Notice to XLCA on
the later of (a) one (1) Business Day following receipt by XLCA of a Payment
Notice or (b) the Business Day on which Scheduled Payments are due for payment.

                                      K-4
<PAGE>

                  Subject to the foregoing, if the payment of any amount with
respect to the Scheduled Payment is voided (a "Preference Event") as a result of
an Insolvency Proceeding and as a result of such Preference Event, the Owner is
required to return such voided payment, or any portion of such voided payment,
made in respect of the Insured Obligation (an "Avoided Payment"), XLCA will pay
an amount equal to such Avoided Payment, as and when such payment would
otherwise be due pursuant to the Trust Agreement without regard to acceleration
or prepayment, and upon payment of such Avoided Payment and receipt by XLCA from
the Trustee on behalf of such Owner of (x) a certified copy of a final order of
a court exercising jurisdiction in such Insolvency Proceeding to the effect that
the Owner or the Trustee on behalf of the Owner is required to return any such
payment or portion thereof because such payment was voided under applicable law,
with respect to which order the appeal period has expired without an appeal
having been filed (the "Final Order"), (y) an assignment, substantially in the
form attached hereto as Exhibit B, properly completed and executed by such Owner
irrevocably assigning to XLCA all rights and claims of such Owner relating to or
arising under such Avoided Payment and (z) a Payment Notice in the form of
Exhibit A hereto appropriately completed and executed by the Trustee.

                  XLCA shall make payments due in respect of Avoided Payments no
later than 2:00 p.m. New York City time on the Business Day following XLCA's
receipt of the documents required under clauses (x) through (z) of the preceding
paragraph. Any such documents received by XLCA after 10:00 a.m. New York City
time on any Business Day or on any day that is not a Business Day shall be
deemed to have been received by XLCA at 9:00 a.m., New York City time, on the
next succeeding Business Day. All payments made by XLCA hereunder on account of
any Avoided Payment shall be disbursed to the receiver, conservator,
debtor-in-possession or trustee in bankruptcy named in the Final Order and not
to any Holder directly (unless a Holder previously paid such amount to the
receiver, conservator, debtor-in-possession or trustee in bankruptcy named in
the Final Order, in which case such payment shall be disbursed to the Trustee
for distribution to such Holder upon proof of such payment reasonably
satisfactory to XLCA).

                  XLCA hereby waives and agrees not to assert any and all rights
to require the Trustee to make demand on or to proceed against any person, party
or security prior to the Trustee demanding payment under this Policy.

                  No defenses, set-offs and counterclaims of any kind available
to XLCA so as to deny payment of any amount due in respect of this Policy will
be valid and XLCA hereby waives and agrees not to assert any and all such
defenses (including, without limitation, defense of fraud in the inducement or
fact, or any other circumstances which would have the effect of discharging a
surety in law or in equity), set-offs and counterclaims, including, without
limitation, any such rights acquired by subrogation, assignment or otherwise.
Upon any payment hereunder, in furtherance and not in limitation of XLCA's
equitable right of subrogation and XLCA's rights under the Insurance Agreement,
XLCA will be subrogated to the rights of the Owner in respect of which such
payment was made to receive any and all amounts due in respect of the
obligations in respect of which XLCA has made a payment hereunder. Any rights of
subrogation acquired by XLCA as a result of any payment made under this Policy
shall, in all respects, be subordinate and junior in right of payment to the
prior indefeasible payment in full of any amounts due the Owner on account of
payments due under the Insured Obligation.

                                      K-5
<PAGE>

                  This Policy does not cover Relief Act Interest Shortfalls,
interest shortfalls due to Payoffs or curtailments, shortfalls, if any,
attributable to the liability of the Obligor or the Beneficiary for withholding
taxes, if any, (including interest and penalties in respect of any liability for
withholding taxes) or any risk other than Nonpayment, including the failure of
the Beneficiary to make any payment required under the Trust Agreement to the
Owners.

                  This Policy is neither transferable nor assignable, in whole
or in part, except to a successor trustee duly appointed and qualified under the
Trust Agreement. All Payment Notices and other notices, presentations,
transmissions, deliveries and communications made by the Trustee to XLCA with
respect to this Policy shall specifically refer to the number of this Policy and
shall be made to XLCA at:

                             XL Capital Assurance Inc.
                             1221 Avenue of the Americas
                             New York, New York 10020
                             Attention: Surveillance
                             Telephone: (212) 478-3400
                             Facsimile:  (212) 478- 3597

         or such other address, telephone number or facsimile number as XLCA may
designate to the Trustee in writing from time to time. Each such Payment Notice
and other notice, presentation, transmission, delivery and communication shall
be effective only upon actual receipt by XLCA.

                  The obligations of XLCA under this Policy are irrevocable,
primary, absolute and unconditional, subject to satisfaction of the conditions
for making a claim under the Policy, and neither the failure of any Person to
perform any covenant or obligation in favor of XLCA (or otherwise), nor the
failure or omission to make a demand permitted hereunder, nor the failure of any
assignment or grant of any security interest, nor the commencement of any
Insolvency Proceeding shall in any way affect or limit XLCA's obligations under
this Policy. If a successful action or proceeding to enforce this Policy is
brought by the Trustee, the Trustee shall be entitled to recover from XLCA costs
and expenses reasonably incurred, including, without limitation, reasonable fees
and expenses of counsel.

                  This Policy and the obligations of XLCA hereunder shall
terminate on the expiration of the Term of this Policy. This Policy shall be
returned to XLCA by the Trustee upon the expiration of the Term of this Policy.

                  The Property/Casualty Insurance Security Fund specified in
Article 76 of the New York Insurance Law does not cover this Policy. The Florida
Insurance Guaranty Association created under Part II of Chapter 631 of the
Florida Insurance Code does not cover this Policy. In the event that XLCA were
to become insolvent, the California Insurance Guaranty Association, established
pursuant to Article 14.2 of Chapter 1 of Part 2 of Division 1 of the California
Insurance Code excludes from coverage any claims arising under this Policy.

                  THIS POLICY SHALL BE CONSTRUED, AND THE OBLIGATIONS, RIGHTS
AND REMEDIES OF THE PARTIES HEREUNDER SHALL BE DETERMINED, IN ACCORDANCE WITH
THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO CONFLICT OF LAWS PRINCIPLES
THAT WOULD REQUIRE THE APPLICATION OF THE LAWS OF ANY OTHER JURISDICTION.

                                      K-6
<PAGE>

                  In the event any term or provision of the form of this Policy
is inconsistent with the provision of this Endorsement, the provision of this
Endorsement shall take precedence and be binding.

                  [Remainder of Page Intentionally Left Blank]



                                      K-7
<PAGE>




                  IN WITNESS WHEREOF, XL Capital Assurance Inc. has caused this
Endorsement to the Policy to be executed on the Effective Date.



         ____________________                      ___________________________
         Name:                                     Name:
         Title:                                    Title:









                                      K-8
<PAGE>



               Exhibit A to Financial Guaranty Policy No. CA00859A

         XL Capital Assurance Inc.
         1221 Avenue of the Americas
         New York, New York 10020
         Attention: Surveillance

                                 PAYMENT NOTICE
                  UNDER FINANCIAL GUARANTY POLICY No. CA00859A

                  [Identify Trustee] as Trustee (the "Trustee"), hereby
certifies to XL Capital Assurance Inc. ("XLCA") with reference to that certain
Financial Guaranty Policy, No. CA00859A dated February 26, 2004 (the "Policy"),
issued by XLCA in favor of the Trustee on behalf of the Owner under the Trust
Agreement, dated as of February 26, 2004 (the "Trust Agreement"), between the
WaMu Mortgage Pass-Through Certificates Series 2004-RS1 Trust and the Trustee,
as follows:

                  1. The Trustee is the trustee under the Trust Agreement and
the beneficiary on behalf of each Owner of the Policy.

                  2. Trustee is entitled to make a demand under the Policy
pursuant to Section __ of the Trust Agreement.

                  3. This notice relates to the [insert date] Distribution Date.
The amount demanded is to be paid in immediately available funds to the [Specify
Account] at [Identify Financial Institution Holding Account] account
number[_____].

         [For a Payment Notice in respect of Insured Amounts other than Avoided
Payment, use paragraph 4.]

                  4. The Trustee demands payment of $________ which is an amount
equal to the amount by which the [Describe calculation of Insured Amount under
Policy].

         [For a Payment Notice in respect of an Avoided Payment use the
following paragraphs [4] or [5].]

[4.] or [5.] The Trustee hereby represents and warrants, based upon information
available to it, that (i) the amount entitled to be drawn under the Policy on
the date hereof in respect of Avoided Payments is the amount paid or to be paid
simultaneously with such draw on the Policy, by the Owner on account of a
Preference Event [$________] (the "Avoided Payment Amount"), (ii) the Owner with
respect to which the drawing is being made under the Policy has paid or
simultaneously with such draw on the Policy will pay such Avoided Payment
Amount, and (iii) the documents required by the Policy to be delivered in
connection with such Avoided Payment and Avoided Payment Amount have previously
been presented to XLCA or are attached hereto.

                  [6] The Trustee agrees that, following payment of funds by
XLCA, it shall use reasonable efforts to procure (a) that such amounts are
applied directly to the payment of any Insured Amount which is due for payment;


                                      K-9
<PAGE>

(b) that such funds are not applied for any other purpose; and (c) the
maintenance of accurate record of such payments in respect of the Insured
Obligation and the corresponding claim on the Policy and the proceeds thereof.

                  [7] The Trustee, on behalf of itself and the Owners, hereby
assigns to XLCA all rights and claims (including rights of actions and claims in
respect of securities laws violations or otherwise) of the Trustee and the
Owners with respect to the Insured Obligation to the extent of any payments
under the Policy. The foregoing assignment is in addition to, and not in
limitation of, rights of subrogation otherwise available to XLCA in respect of
such payments. The Trustee shall take such action and deliver such instruments
as may be reasonably required by XLCA to effectuate the purposes of provisions [
] of this Clause 7.

                  [8] The Trustee, on behalf of itself and the Owners, hereby
appoints XLCA as agent and attorney-in-fact for the Trustee and the Owners in
any legal proceeding in respect of the Insured Obligation. The Trustee, on
behalf of itself and the Owners, thereby (and without limiting the generality of
the preceding sentence) agrees that XLCA may at any time during the continuation
of any proceeding by or against any debtor with respect to which a Preference
Claim (as defined below) or other claim with respect to the Insured Obligation
is asserted under any Insolvency Proceeding, direct all matters relating to such
Insolvency Proceeding, including, without limitation, (a) all matters relating
to any claim in connection with a Insolvency Proceeding seeking the avoidance as
a preferential transfer of any payment made with respect to the obligations (a
"Preference Claim"), (b) the direction of any appeal of any order relating to
any Preference Claim and (c) the posting of any surety, supersedes or
performance bond pending any such appeal. In addition, the Trustee, on behalf of
itself and the Owners, hereby agrees that XLCA shall be subrogated to, and the
Trustee, on behalf of itself and the Owners, hereby delegates and assigns, to
the fullest extent permitted by law, the rights of the Trustee and the Owners in
the conduct of any Insolvency Proceeding, including, without limitation, all
rights of any party to an adversary proceeding or action with respect to any
court order issued in connection with any such Insolvency Proceeding.

                  Capitalized terms used herein and not otherwise defined herein
shall have the meanings assigned to them in the Policy or [Identify Document]

                  IN WITNESS WHEREOF, this notice has been executed this ____
day of ________, ____.

                                        ________________________, as Trustee
                                        By:_____________________
                                           Authorized Officer


Any Person Who Knowingly And With Intent To Defraud Any Insurance Company Or
Other Person Files An Application For Insurance Or Statement Of Claim Containing
Any Materially False Information, Or Conceals For The Purpose Of Misleading
Information Concerning Any Fact Material Thereof, Commits A Fraudulent Insurance
Act, Which Is A Crime, And Shall Also Be Subject To A Civil Penalty Not To
Exceed Five Thousand Dollars And The Stated Value Of The Claim For Each Such
Violation



                                      K-10
<PAGE>

         Exhibit B to Financial Guaranty Insurance Policy, No. CA00859A

         Form of Assignment

                  Reference is made to the Financial Guaranty Insurance Policy
No. CA00859A, dated February 26, 2004 (together with the Endorsement attached
thereto, the "Policy") issued by XL Capital Assurance Inc. ("XLCA") relating to
the $15,000,000 5.50% WaMu Mortgage Pass-Through Certificates, Series 2004-RS1,
Class A-3 Certificates. Unless otherwise defined herein, 1capitalized terms used
in this Assignment shall have the meanings assigned thereto in the Policy as
incorporated by reference therein. In connection with the Avoided Payment of [$
] paid by the undersigned (the "Owner") on [ ] and the payment by XLCA in
respect of such Avoided Payment pursuant to the Policy, the Owner hereby
irrevocably and unconditionally, without recourse, representation or warranty
(except as provided below), sells, assigns, transfers, conveys and delivers all
of such Owner's rights, title and interest in and to any rights or claims,
whether accrued, contingent or otherwise, which the Owner now has or may
hereafter acquire, against any person relating to, arising out of or in
connection with such Avoided Payment. The Owner represents and warrants that
such claims and rights are free and clear of any lien or encumbrance created or
incurred by such Owner.

                                            _________________________
                                            Owner




________________________

                  1 In the event that the terms of this form of assignment are
reasonably determined to be insufficient solely as a result of a change of law
or applicable rules after the date of the Policy to fully vest all of the
Owner's right, title and interest in such rights and claims, the Owner and XLCA
shall agree on such other form as is reasonably necessary to effect such
assignment, which assignment shall be without recourse, representation or
warranty except as provided above.



                                      K-11