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                                                                     Exhibit 4.6

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                           TRUST PREFERRED SECURITIES
                               GUARANTEE AGREEMENT

                              COASTAL BANCORP, INC.

                          DATED AS OF _______ __ , 2002

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                                TABLE OF CONTENTS

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                                                                                                PAGE
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                                    ARTICLE I
                         DEFINITIONS AND INTERPRETATION

SECTION 1.1    DEFINITIONS AND INTERPRETATION......................................................1

                                   ARTICLE II
                               TRUST INDENTURE ACT

SECTION 2.1    TRUST INDENTURE ACT; APPLICATION....................................................5
SECTION 2.2    LISTS OF HOLDERS OF TRUST PREFERRED SECURITIES......................................5
SECTION 2.3    REPORTS BY THE TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE.........................6
SECTION 2.4    PERIODIC REPORTS TO TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE....................6
SECTION 2.5    EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT....................................6
SECTION 2.6    GUARANTEE EVENTS OF DEFAULT; WAIVER.................................................6
SECTION 2.7    GUARANTEE EVENT OF DEFAULT; NOTICE..................................................7
SECTION 2.8    CONFLICTING INTERESTS...............................................................7

                                   ARTICLE III
                          POWERS, DUTIES AND RIGHTS OF
                  TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

SECTION 3.1    POWERS AND DUTIES OF THE TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE...............7
SECTION 3.2    CERTAIN RIGHTS OF TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE......................9
SECTION 3.3    NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF TRUST PREFERRED SECURITIES GUARANTEE...11

                                   ARTICLE IV
                  TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

SECTION 4.1    TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE; ELIGIBILITY..........................11
SECTION 4.2    APPOINTMENT, REMOVAL AND RESIGNATION OF TRUST PREFERRED
                     SECURITIES GUARANTEE TRUSTEE.................................................12

                                    ARTICLE V
                                    GUARANTEE

SECTION 5.1    GUARANTEE..........................................................................13
SECTION 5.2    WAIVER OF NOTICE AND DEMAND........................................................13
SECTION 5.3    OBLIGATIONS NOT AFFECTED...........................................................13
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SECTION 5.4    RIGHTS OF HOLDERS..................................................................14
SECTION 5.5    GUARANTEE OF PAYMENT...............................................................15
SECTION 5.6    SUBROGATION........................................................................15
SECTION 5.7    INDEPENDENT OBLIGATIONS............................................................15

                                   ARTICLE VI
                    LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 6.1    LIMITATION OF TRANSACTIONS.........................................................15
SECTION 6.2    RANKING............................................................................16

                                   ARTICLE VII
                                   TERMINATION

SECTION 7.1    TERMINATION........................................................................16

                                  ARTICLE VIII
                                 INDEMNIFICATION

SECTION 8.1    EXCULPATION........................................................................17
SECTION 8.2    INDEMNIFICATION....................................................................17

                                   ARTICLE IX
                                  MISCELLANEOUS

SECTION 9.1    SUCCESSORS AND ASSIGNS.............................................................17
SECTION 9.2    AMENDMENTS.........................................................................18
SECTION 9.3    NOTICES............................................................................18
SECTION 9.4    BENEFIT............................................................................19
SECTION 9.5    GOVERNING LAW......................................................................19
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                                       ii
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                 TRUST PREFERRED SECURITIES GUARANTEE AGREEMENT

          This Trust Preferred Securities Guarantee Agreement (the "Trust
Preferred Securities Guarantee"), dated as of _______ __, 2002, is executed and
delivered by Coastal Bancorp, Inc., a Texas corporation (the "Guarantor"), and
The Bank of New York, a New York banking corporation, as trustee, for the
benefit of the Holders (as defined herein) from time to time of the Trust
Preferred Securities (as defined herein) of Coastal Capital Trust I, a Delaware
statutory business trust (the"Issuer").

          WHEREAS, pursuant to an Amended and Restated Declaration of Trust (the
"Declaration"), dated as of _______ _, 2002, among the trustees of the Issuer
named therein, the Guarantor, as sponsor, and the Holders from time to time of
undivided beneficial interests in the assets of the Issuer, the Issuer is
issuing on the date hereof, __________ trust preferred securities, having an
aggregate liquidation amount of $_________, such trust preferred securities
being designated the ____% Cumulative Trust Preferred Securities (collectively
the "Trust Preferred Securities"); and

          WHEREAS, as incentive for the Holders to purchase the Trust Preferred
Securities, the Guarantor desires irrevocably and unconditionally to agree, to
the extent set forth in this Trust Preferred Securities Guarantee, to pay to the
Holders the Guarantee Payments (as defined herein) and to make certain other
payments on the terms and conditions set forth herein; and

          WHEREAS, the Guarantor is executing and delivering a guarantee
agreement (the "Common Securities Guarantee"), with substantially identical
terms to this Trust Preferred Securities Guarantee, for the benefit of the
holders of the Common Securities (as defined herein), except that if an Event of
Default (as defined in the Declaration) has occurred and is continuing, the
rights of holders of the Common Securities to receive Guarantee Payments under
the Common Securities Guarantee are subordinated, to the extent and in the
manner set forth in the Common Securities Guarantee, to the rights of holders of
Trust Preferred Securities to receive Guarantee Payments under this Trust
Preferred Securities Guarantee;

          NOW, THEREFORE, in consideration of the purchase by each Holder, which
purchase the Guarantor hereby acknowledges shall benefit the Guarantor, the
Guarantor executes and delivers this Trust Preferred Securities Guarantee for
the benefit of the Holders.

                                    ARTICLE I
                         DEFINITIONS AND INTERPRETATION

SECTION 1.1    DEFINITIONS AND INTERPRETATION

               In this Trust Preferred Securities Guarantee, unless the context
otherwise requires:

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               (a)  capitalized terms used in this Trust Preferred Securities
                    Guarantee but not defined in the preamble above have the
                    respective meanings assigned to them in this Section 1.1;

               (b)  a term defined in the Declaration as at the date of
                    execution of this Trust Preferred Securities Guarantee have
                    the same meaning when used in this Trust Preferred
                    Securities Guarantee unless otherwise defined in this Trust
                    Preferred Securities Guarantee;

               (c)  a term defined anywhere in this Trust Preferred Securities
                    Guarantee has the same meaning throughout;

               (d)  all references to "the Trust Preferred Securities Guarantee"
                    or "this Trust Preferred Securities Guarantee" are to this
                    Trust Preferred Securities Guarantee as modified,
                    supplemented or amended from time to time;

               (e)  all references in this Trust Preferred Securities Guarantee
                    to Articles and Sections are to Articles and Sections of
                    this Trust Preferred Securities Guarantee, unless otherwise
                    specified;

               (f)  a term defined in the Trust Indenture Act has the same
                    meaning when used in this Trust Preferred Securities
                    Guarantee, unless otherwise defined in this Trust Preferred
                    Securities Guarantee or unless the context otherwise
                    requires; and

               (g)  a reference to the singular includes the plural and vice
                    versa.

               "AFFILIATE" has the same meaning as given to that term in Rule
405 under the Securities Act of 1933, as amended, or any successor rule
thereunder.

               "BUSINESS DAY" means any day other than a Saturday or a Sunday,
or a day on which banking institutions in the City of New York or Houston, Texas
are authorized or required by law or executive order to close.

               "COMMON SECURITIES" means the securities representing common
undivided beneficial interests in the assets of the Issuer.

               "CORPORATE TRUST OFFICE" means the office of the Trust Preferred
Securities Guarantee Trustee at which the corporate trust business of the Trust
Preferred Securities Guarantee Trustee shall, at any particular time, be
principally administered, which office at the date of execution of this Trust
Preferred Securities Guarantee is located at 5 Penn Plaza, 13th Floor, New York,
New York 10001.

               "COVERED PERSON" means any Holder or beneficial owner of Trust
Preferred Securities.

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               "DEBENTURES" means the series of subordinated deferrable interest
debentures of the Guarantor designated the ___% Junior Subordinated Deferrable
Interest Debentures due _________ _, 2032 held by the Property Trustee (as
defined in the Declaration) of the Issuer.

               "GUARANTEE EVENT OF DEFAULT" means a default by the Guarantor on
any of its payment or other obligations under this Trust Preferred Securities
Guarantee; provided, however, that except with respect to a default in payment
of any Guarantee Payment, the Guarantor shall have received notice of default
and shall not have cured such default within 60 days after receipt of such
notice.

               "GUARANTEE PAYMENTS" means the following payments or
distributions, without duplication, with respect to the Trust Preferred
Securities, to the extent not paid or made by the Issuer: (i) any accumulated
and unpaid Distributions (as defined in the Declaration) that are required to be
paid on such Trust Preferred Securities to the extent the Issuer has funds on
hand legally available therefor at such time; (ii) the redemption price,
including all accumulated and unpaid Distributions to the date of redemption
(the "Redemption Price") to the extent the Issuer has funds on hand legally
available therefor at such time, with respect to any Trust Preferred Securities
called for redemption by the Issuer; and (iii) upon a voluntary or involuntary
dissolution or winding up of the Issuer (other than in connection with the
distribution of Debentures to the Holders in exchange for Trust Preferred
Securities as provided in the Declaration), the lesser of (a) the aggregate of
the liquidation amount and all accumulated and unpaid Distributions on the Trust
Preferred Securities to the date of payment, to the extent the Issuer has funds
on hand legally available therefor, and (b) the amount of assets of the Issuer
remaining available for distribution to Holders in liquidation of the Issuer
after satisfaction of liabilities to creditors (in either case, the "Liquidation
Distribution"). If an Event of Default has occurred and is continuing, no
Guarantee Payments under the Common Securities Guarantee with respect to the
Common Securities or any guarantee payment under any Other Common Securities
Guarantees shall be made until the Holders shall be paid in full the Guarantee
Payments to which they are entitled under this Trust Preferred Securities
Guarantee.

               "HOLDER" shall mean any holder, as registered on the books and
records of the Issuer, of any Trust Preferred Securities; provided, however,
that, in determining whether the holders of the requisite percentage of Trust
Preferred Securities have given any request, notice, consent or waiver
hereunder, "Holder" shall not include the Guarantor or any Affiliate of the
Guarantor.

               "INDEMNIFIED PERSON" means the Trust Preferred Securities
Guarantee Trustee, any Affiliate of the Trust Preferred Securities Guarantee
Trustee, or any officers, directors, shareholders, members, partners, employees,
representatives, nominees, custodians or agents of the Trust Preferred
Securities Guarantee Trustee.

               "INDENTURE" means the Indenture dated as of _______ _, 2002,
among the Guarantor (the "Debenture Issuer") and The Bank of New York, as
trustee (the "Indenture Trustee"), pursuant to which the Debentures are to be
issued to the Property Trustee of the Issuer.

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               "INDENTURE EVENT OF DEFAULT" shall mean any event specified in
Section 5.01 of the Indenture.

               "MAJORITY IN LIQUIDATION AMOUNT OF THE TRUST PREFERRED
SECURITIES" means, except as provided by the Declaration, the terms of the
Preferred Securities or by the Trust Indenture Act, a vote by Holder(s) of more
than 50% of the aggregate liquidation amount of all Trust Preferred Securities.
In determining whether the Holders of the requisite amount of Trust Preferred
Securities have voted, Trust Preferred Securities which are owned by the
Guarantor or any Affiliate of the Guarantor or any other obligor on the Trust
Preferred Securities shall be disregarded for the purpose of any such
determination.

               "OFFICERS' CERTIFICATE" means, with respect to the Guarantor, a
certificate signed by any two of the following: the Chairman, a Vice Chairman,
the Chief Executive Officer, the President, a Vice President, the Comptroller,
the Secretary or an Assistant Secretary of the Guarantor. Any Officers'
Certificate delivered with respect to compliance with a condition or covenant
provided for in this Trust Preferred Securities Guarantee (other than pursuant
to Section 314(d)(4) of the Trust Indenture Act) shall include:

               (a)  a statement that each officer signing the Officers'
          Certificate has read the covenant or condition and the definitions
          relating thereto;

               (b)  a statement that each such officer has made such examination
          or investigation as, in such officer's opinion, is necessary to enable
          such officer to express an informed opinion as to whether or not such
          covenant or condition has been complied with; and

               (c)  a statement as to whether, in the opinion of each such
          officer, such condition or covenant has been complied with.

               "OTHER COMMON SECURITIES GUARANTEES" shall have the same meaning
as "Other Guarantees" as defined in the Common Securities Guarantee.

               "OTHER DEBENTURES" means all junior subordinated debentures
issued by the Guarantor from time to time and sold to trusts to be established
by the Guarantor, in each case similar to the Issuer.

               "OTHER GUARANTEES" means all guarantees issued or to be issued by
the Guarantor with respect to trust preferred securities similar to the Trust
Preferred Securities issued by other trusts established or to be established by
the Guarantor, in each case similar to the Issuer.

               "PERSON" means a legal person, including any individual,
corporation, estate, partnership, joint venture, association, joint stock
company, limited liability company, trust, unincorporated association, or
government or any agency or political subdivision thereof, or any other entity
of whatever nature.

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               "RESPONSIBLE OFFICER" means, with respect to the Trust Preferred
Securities Guarantee Trustee, any officer within the Corporate Trust Office of
the Trust Preferred Securities Guarantee Trustee with direct responsibility for
the administration of this Trust Preferred Securities Guarantee and also means,
with respect to a particular corporate trust matter, any other officer to whom
such matter is referred because of that officer's knowledge of and familiarity
with the particular subject.

               "SUCCESSOR TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE" means a
successor Trust Preferred Securities Guarantee Trustee possessing the
qualifications to act as Trust Preferred Securities Guarantee Trustee under
Section 4.1.

               "TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE" means The Bank of
New York, a New York banking corporation, until a Successor Trust Preferred
Securities Guarantee Trustee has been appointed and has accepted such
appointment pursuant to the terms of this Trust Preferred Securities Guarantee
and thereafter means each such Successor Trust Preferred Securities Guarantee
Trustee.

               "TRUST INDENTURE ACT" means the Trust Indenture Act of 1939, as
amended from time to time, or any successor legislation.

               "TRUST SECURITIES" means the Common Securities and the Trust
Preferred Securities, collectively.

                                   ARTICLE II
                               TRUST INDENTURE ACT

SECTION 2.1    TRUST INDENTURE ACT; APPLICATION

               (a)  This Trust Preferred Securities Guarantee is subject to the
provisions of the Trust Indenture Act that are required to be part of this Trust
Preferred Securities Guarantee and shall, to the extent applicable, be governed
by such provisions; and

               (b)  if and to the extent that any provision of this Trust
Preferred Securities Guarantee limits, qualifies or conflicts with the duties
imposed by Section 310 to 317, inclusive, of the Trust Indenture Act, such
imposed duties shall control.

SECTION 2.2    LISTS OF HOLDERS OF TRUST PREFERRED SECURITIES

               (a)  The Guarantor shall provide the Trust Preferred Securities
Guarantee Trustee (unless the Trust Preferred Securities Guarantee Trustee is
otherwise the registrar of the Trust Preferred Securities) with a list, in such
form as the Trust Preferred Securities Guarantee Trustee may reasonably require,
of the names and addresses of the Holders of the Trust Preferred Securities
("List of Holders") as of such date, (i) within 14 days after each record date
for payment of Distributions, as defined in the Declaration, and (ii) at any
other time within 30 days of receipt by the Guarantor of a written request for a
List of Holders as of a date no more than 14

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days before such List of Holders is given to the Trust Preferred Securities
Guarantee Trustee, provided, that the Guarantor shall not be obligated to
provide such List of Holders at any time the List of Holders does not differ
from the most recent List of Holders given to the Trust Preferred Securities
Guarantee Trustee by the Guarantor. The Trust Preferred Securities Guarantee
Trustee shall preserve, in as current a form as is reasonably practicable, all
information contained in a List of Holders given to it, provided that it may
destroy any List of Holders previously given to it on receipt of a new List of
Holders.

               (b)  The Trust Preferred Securities Guarantee Trustee shall
comply with its obligations under Sections 311(a), 311(b) and Section 312(b) of
the Trust Indenture Act.

SECTION 2.3    REPORTS BY THE TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

               Within 60 days after May 15 of each year, commencing May 15,
2002, the Trust Preferred Securities Guarantee Trustee shall provide to the
Holders such reports as are required by Section 313 of the Trust Indenture Act,
if any, in the form and in the manner provided by Section 313 of the Trust
Indenture Act. The Trust Preferred Securities Guarantee Trustee shall also
comply with the other requirements of Section 313 of the Trust Indenture Act.

SECTION 2.4    PERIODIC REPORTS TO TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

               The Guarantor shall provide to the Trust Preferred Securities
Guarantee Trustee such documents, reports and information as required by Section
314 of the Trust Indenture Act (if any) and the compliance certificate required
by Section 314 of the Trust Indenture Act in the form, in the manner and at the
times required by Section 314 of the Trust Indenture Act, provided that such
compliance certificate shall be delivered on or before 120 days after the end of
each fiscal year of the Guarantor.

SECTION 2.5    EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT

               The Guarantor shall provide to the Trust Preferred Securities
Guarantee Trustee such evidence of compliance with any conditions precedent, if
any, provided for in this Trust Preferred Securities Guarantee that relate to
any of the matters set forth in Section 314(c) of the Trust Indenture Act. Any
certificate or opinion required to be given by an officer pursuant to Section
314(c)(1) may be given in the form of an Officers' Certificate.

SECTION 2.6    GUARANTEE EVENTS OF DEFAULT; WAIVER

               The Holders of a Majority in liquidation amount of Trust
Preferred Securities may, by vote or by written consent, on behalf of all
Holders, waive any past Guarantee Event of Default and its consequences. Upon
such waiver, any such Guarantee Event of Default shall cease to exist, and any
Guarantee Event of Default arising therefrom shall be deemed to have been cured,
for every purpose of this Trust Preferred Securities Guarantee, but no such
waiver shall extend to any subsequent or other default or Guarantee Event of
Default or impair any right consequent thereon.

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SECTION 2.7    GUARANTEE EVENT OF DEFAULT; NOTICE

               (a)  The Trust Preferred Securities Guarantee Trustee shall,
within 90 days after the occurrence of a Guarantee Event of Default, mail by
first class postage prepaid, to all Holders, notices of all Guarantee Events of
Default actually known to a Responsible Officer, unless such defaults have been
cured before the giving of such notice; provided, that, except in the case of a
Guarantee Event of Default in the timing or payment of any Guarantee Payment,
the Trust Preferred Securities Guarantee Trustee shall be protected in
withholding such notice if and so long as the board of directors, the executive
committee, or a trust committee of directors and/or a Responsible Officer of the
Trust Preferred Securities Guarantee Trustee in good faith determines that the
withholding of such notice is in the interests of the Holders.

               (b)  The Trust Preferred Securities Guarantee Trustee shall not
be deemed to have knowledge of any Guarantee Event of Default unless the Trust
Preferred Securities Guarantee Trustee shall have received written notice from
the Guarantor, or a Responsible Officer charged with the administration of this
Trust Preferred Securities Guarantee shall have obtained actual knowledge, of
such Guarantee Event of Default.

SECTION 2.8    CONFLICTING INTERESTS

               The Declaration shall be deemed to be specifically described in
this Trust Preferred Securities Guarantee for the purposes of clause (i) of the
first proviso contained in Section 310(b) of the Trust Indenture Act.

                                   ARTICLE III
                          POWERS, DUTIES AND RIGHTS OF
                  TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

SECTION 3.1    POWERS AND DUTIES OF THE TRUST PREFERRED SECURITIES GUARANTEE
               TRUSTEE

               (a)  This Trust Preferred Securities Guarantee shall be held by
the Trust Preferred Securities Guarantee Trustee for the benefit of the Holders,
and the Trust Preferred Securities Guarantee Trustee shall not transfer this
Trust Preferred Securities Guarantee to any Person except a Holder exercising
his, her or its rights pursuant to Section 5.4(b) or to a Successor Trust
Preferred Securities Guarantee Trustee on acceptance by such Successor Trust
Preferred Securities Guarantee Trustee of its appointment to act as Successor
Trust Preferred Securities Guarantee Trustee. The right, title and interest of
the Trust Preferred Securities Guarantee Trustee shall automatically vest in any
Successor Trust Preferred Securities Guarantee Trustee, and such vesting and
succession of title shall be effective whether or not conveyancing documents
have been executed and delivered pursuant to the appointment of such Successor
Trust Preferred Securities Guarantee Trustee.

               (b)  If a Guarantee Event of Default actually known to a
Responsible Officer has occurred and is continuing, the Trust Preferred
Securities Guarantee Trustee shall enforce this Trust Preferred Securities
Guarantee for the benefit of the Holders.

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               (c)  The Trust Preferred Securities Guarantee Trustee, before the
occurrence of any Guarantee Event of Default and after the curing of all
Guarantee Events of Default that may have occurred, shall undertake to perform
only such duties as are specifically set forth in this Trust Preferred
Securities Guarantee, and no implied covenants shall be read into this Trust
Preferred Securities Guarantee against the Trust Preferred Securities Guarantee
Trustee. In case a Guarantee Event of Default has occurred (that has not been
cured or waived pursuant to Section 2.6) and is actually known to a Responsible
Officer, the Trust Preferred Securities Guarantee Trustee shall exercise such of
the rights and powers vested in it by this Trust Preferred Securities Guarantee,
and use the same degree of care and skill in its exercise thereof, as a prudent
person would exercise or use under the circumstances in the conduct of his or
her own affairs.

               (d)  No provision of this Trust Preferred Securities Guarantee
shall be construed to relieve the Trust Preferred Securities Guarantee Trustee
from liability for its own negligent action, its own negligent failure to act,
or its own willful misconduct, except that:

                    (i)  prior to the occurrence of any Guarantee Event of
     Default and after the curing or waiving of all such Guarantee Events of
     Default that may have occurred:

                         (A) the duties and obligations of the Trust Preferred
                    Securities Guarantee Trustee shall be determined solely by
                    the express provisions of this Trust Preferred Securities
                    Guarantee, and the Trust Preferred Securities Guarantee
                    Trustee shall not be liable except for the performance of
                    such duties and obligations as are specifically set forth in
                    this Trust Preferred Securities Guarantee, and no implied
                    covenants or obligations shall be read into this Trust
                    Preferred Securities Guarantee against the Trust Preferred
                    Securities Guarantee Trustee; and

                         (B) in the absence of bad faith on the part of the
                    Trust Preferred Securities Guarantee Trustee, the Trust
                    Preferred Securities Guarantee 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 the Trust Preferred Securities
                    Guarantee Trustee and conforming to the requirements of this
                    Trust Preferred Securities Guarantee; but in the case of any
                    such certificates or opinions that by any provision hereof
                    are specifically required to be furnished to the Trust
                    Preferred Securities Guarantee Trustee, the Trust Preferred
                    Securities Guarantee Trustee shall be under a duty to
                    examine the same to determine whether or not they conform to
                    the requirements of this Trust Preferred Securities
                    Guarantee (but need not confirm or investigate the accuracy
                    of mathematical calculations or other facts stated therein);

                    (ii) the Trust Preferred Securities Guarantee Trustee shall
     not be liable for any error of judgment made in good faith by a Responsible
     Officer, unless it shall be

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     proved that the Trust Preferred Securities Guarantee Trustee was negligent
     in ascertaining the pertinent facts upon which such judgment was made;

                    (iii) the Trust Preferred Securities Guarantee Trustee shall
     not be liable with respect to any action taken or omitted to be taken by it
     in good faith in accordance with the direction of the Holders of a Majority
     in liquidation amount of the Trust Preferred Securities relating to the
     time, method and place of conducting any proceeding for any remedy
     available to the Trust Preferred Securities Guarantee Trustee, or
     exercising any trust or power conferred upon the Trust Preferred Securities
     Guarantee Trustee under this Trust Preferred Securities Guarantee; and

                    (iv) no provision of this Trust Preferred Securities
     Guarantee shall require the Trust Preferred Securities Guarantee Trustee to
     expend or risk its own funds or otherwise incur personal financial
     liability in the performance of any of its duties or in the exercise of any
     of its rights or powers, if the Trust Preferred Securities Guarantee
     Trustee shall have reasonable grounds for believing that the repayment of
     such funds or liability is not reasonably assured to it under the terms of
     this Trust Preferred Securities Guarantee or indemnity, reasonably
     satisfactory to the Trust Preferred Securities Guarantee Trustee, against
     such risk or liability is not reasonably assured to it.

SECTION 3.2    CERTAIN RIGHTS OF TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

               (a)  Subject to the provisions of Section 3.1:

                    (i)   The Trust Preferred Securities Guarantee Trustee may
     conclusively rely, and shall be fully protected in acting or refraining
     from acting, upon any resolution, certificate, statement, instrument,
     opinion, report, notice, request, direction, consent, order, bond,
     debenture, note, other evidence of indebtedness or other paper or document
     believed by it to be genuine and to have been signed, sent or presented by
     the proper party or parties.

                    (ii)  Any direction or act of the Guarantor contemplated by
     this Trust Preferred Securities Guarantee may be sufficiently evidenced by
     an Officers' Certificate.

                    (iii) Whenever, in the administration of this Trust
     Preferred Securities Guarantee, the Trust Preferred Securities Guarantee
     Trustee shall deem it desirable that a matter be proved or established
     before taking, suffering or omitting any action hereunder, the Trust
     Preferred Securities Guarantee Trustee (unless other evidence is herein
     specifically prescribed) may, in the absence of bad faith on its part,
     request and conclusively rely upon an Officers' Certificate which, upon
     receipt of such request, shall be promptly delivered by the Guarantor.

                    (iv)  The Trust Preferred Securities Guarantee Trustee shall
     have no duty to see to any recording, filing or registration of any
     instrument (or any rerecording, refilling or registration thereof).

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                    (v)   The Trust Preferred Securities Guarantee Trustee may
     consult with counsel of its selection, and the advice or opinion of such
     counsel with respect to legal matters shall be full and complete
     authorization and protection in respect of any action taken, suffered or
     omitted by it hereunder in good faith and in accordance with such advice or
     opinion. Such counsel may be counsel to the Guarantor or any of its
     Affiliates and may include any of its employees. The Trust Preferred
     Securities Guarantee Trustee shall have the right at any time to seek
     instructions concerning the administration of this Trust Preferred
     Securities Guarantee from any court of competent jurisdiction.

                    (vi)  The Trust Preferred Securities Guarantee Trustee shall
     be under no obligation to exercise any of the rights or powers vested in it
     by this Trust Preferred Securities Guarantee at the request or direction of
     any Holder, unless such Holder shall have provided to the Trust Preferred
     Securities Guarantee Trustee such security and indemnity, reasonably
     satisfactory to the Trust Preferred Securities Guarantee Trustee, against
     the costs, expenses (including attorneys' fees and expenses and the
     expenses of the Trust Preferred Securities Guarantee Trustee's agents,
     nominees or custodians) and liabilities that might be incurred by it in
     complying with such request or direction, including such reasonable
     advances as may be requested by the Trust Preferred Securities Guarantee
     Trustee; provided that, nothing contained in this Section 3.2(a)(vi) shall
     be taken to relieve the Trust Preferred Securities Guarantee Trustee, upon
     the occurrence of a Guarantee Event of Default, of its obligation to
     exercise the rights and powers vested in it by this Trust Preferred
     Securities Guarantee.

                    (vii) The Trust Preferred Securities Guarantee Trustee shall
     not be bound to make any investigation into the facts or matters stated in
     any resolution, certificate, statement, instrument, opinion, report,
     notice, request, direction, consent, order, bond, debenture, note, other
     evidence of indebtedness or other paper or document, but the Trust
     Preferred Securities Guarantee Trustee, in its discretion, may make such
     further inquiry or investigation into such facts or matters as it may see
     fit.

                    (viii) The Trust Preferred Securities Guarantee Trustee may
     execute any of the trusts or powers hereunder or perform any duties
     hereunder either directly or by or through agents, nominees, custodians or
     attorneys, and the Trust Preferred Securities Guarantee Trustee shall not
     be responsible for any misconduct or negligence on the part of any agent,
     custodian, nominee or attorney appointed with due care by it hereunder.

                    (ix)  Any action taken by the Trust Preferred Securities
     Guarantee Trustee or its agents hereunder shall bind the Holders, and the
     signature of the Trust Preferred Securities Guarantee Trustee or its agents
     alone shall be sufficient and effective to perform any such action. No
     third party shall be required to inquire as to the authority of the Trust
     Preferred Securities Guarantee Trustee to so act or as to its compliance
     with any of the terms and provisions of this Trust Preferred Securities
     Guarantee, both of which shall be conclusively evidenced by the Trust
     Preferred Securities Guarantee Trustee's or its agent's taking such action.

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                    (x)   Whenever in the administration of this Trust Preferred
     Securities Guarantee the Trust Preferred Securities Guarantee Trustee shall
     deem it desirable to receive instructions with respect to enforcing any
     remedy or right or taking any other action hereunder, the Trust Preferred
     Securities Guarantee Trustee (i) may request instructions from the Holders
     of a Majority in liquidation amount of the Trust Preferred Securities, (ii)
     may refrain from enforcing such remedy or right or taking such other action
     until such instructions are received and (iii) shall be protected in
     conclusively relying on or acting in accordance with such instructions.

                    (xi)  The Trust Preferred Securities Guarantee Trustee shall
     not be liable for any action taken, suffered, or omitted to be taken by it
     in good faith, without negligence, and reasonably believed by it to be
     authorized or within the discretion or rights or powers conferred upon it
     by this Trust Preferred Securities Guarantee.

               (b)  No provision of this Trust Preferred Securities Guarantee
shall be deemed to impose any duty or obligation on the Trust Preferred
Securities Guarantee Trustee to perform any act or acts or exercise any right,
power, duty or obligation conferred or imposed on it in any jurisdiction in
which it shall be illegal, or in which the Trust Preferred Securities Guarantee
Trustee shall be unqualified or incompetent in accordance with applicable law,
to perform any such act or acts or to exercise any such right, power, duty or
obligation. No permissive power or authority available to the Trust Preferred
Securities Guarantee Trustee shall be construed to be a duty.

SECTION 3.3.   NOT RESPONSIBLE FOR RECITALS OR ISSUANCE OF TRUST PREFERRED
               SECURITIES GUARANTEE

               The recitals contained in this Trust Preferred Securities
Guarantee shall be taken as the statements of the Guarantor, and the Trust
Preferred Securities Guarantee Trustee does not assume any responsibility for
their correctness. The Trust Preferred Securities Guarantee Trustee makes no
representation as to the validity or sufficiency of this Trust Preferred
Securities Guarantee.

                                   ARTICLE IV
                  TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE

SECTION 4.1    TRUST PREFERRED SECURITIES GUARANTEE TRUSTEE; ELIGIBILITY

               (a)  There shall at all times be a Trust Preferred Securities
Guarantee Trustee which shall:

                    (i)   not be an Affiliate of the Guarantor; and

                    (ii)  be a corporation organized and doing business under
     the laws of the United States of America or any State or Territory thereof
     or of the District of Columbia, or a corporation or Person permitted by the
     Securities and Exchange Commission to act as an institutional trustee under
     the Trust Indenture Act, authorized

                                       11
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     under such laws to exercise corporate trust powers, having a combined
     capital and surplus of at least 50 million U.S. dollars ($50,000,000), and
     subject to supervision or examination by Federal, State, Territorial or
     District of Columbia authority. If such corporation publishes reports of
     condition at least annually, pursuant to law or to the requirements of the
     supervising or examining authority referred to above, then, for the
     purposes of this Section 4.1(a)(ii), 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.

               (b)  If at any time the Trust Preferred Securities Guarantee
Trustee shall cease to be eligible to so act under Section 4.1(a), the Trust
Preferred Securities Guarantee Trustee shall immediately resign in the manner
and with the effect set out in Section 4.2(c).

               (c)  If the Trust Preferred Securities Guarantee Trustee has or
shall acquire any "conflicting interest" within the meaning of Section 310(b) of
the Trust Indenture Act, the Trust Preferred Securities Guarantee Trustee and
Guarantor shall in all respects comply with the provisions of Section 310(b) of
the Trust Indenture Act.

SECTION 4.2    APPOINTMENT, REMOVAL AND RESIGNATION OF TRUST PREFERRED
               SECURITIES GUARANTEE TRUSTEE

               (a)  Subject to Section 4.2(b), the Trust Preferred Securities
Guarantee Trustee may be appointed or removed without cause at any time by the
Guarantor except during a Guarantee Event of Default.

               (b)  The Trust Preferred Securities Guarantee Trustee shall not
be removed in accordance with Section 4.2(a) until a Successor Trust Preferred
Securities Guarantee Trustee has been appointed and has accepted such
appointment by written instrument executed by such Successor Trust Preferred
Securities Guarantee Trustee and delivered to the Guarantor.

               (c)  The Trust Preferred Securities Guarantee Trustee shall hold
office until a Successor Trust Preferred Securities Guarantee Trustee shall have
been appointed or until its removal or resignation. The Trust Preferred
Securities Guarantee Trustee may resign from office (without need for prior or
subsequent accounting) by an instrument in writing executed by the Trust
Preferred Securities Guarantee Trustee and delivered to the Guarantor, which
resignation shall not take effect until a Successor Trust Preferred Securities
Guarantee Trustee has been appointed and has accepted such appointment by
instrument in writing executed by such Successor Trust Preferred Securities
Guarantee Trustee and delivered to the Guarantor and the resigning Trust
Preferred Securities Guarantee Trustee.

               (d)  If no Successor Trust Preferred Securities Guarantee Trustee
shall have been appointed and accepted appointment as provided in this Section
4.2 within 60 days after delivery of an instrument of removal or resignation,
the Trust Preferred Securities Guarantee Trustee resigning or being removed may
petition any court of competent jurisdiction for appointment of a Successor
Trust Preferred Securities Guarantee Trustee. Such court may

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thereupon, after prescribing such notice, if any, as it may deem proper, appoint
a Successor Trust Preferred Securities Guarantee Trustee.

               (e)  No Trust Preferred Securities Guarantee Trustee shall be
liable for the acts or omissions to act of any Successor Trust Preferred
Securities Guarantee Trustee.

               (f)  Upon termination of this Trust Preferred Securities
Guarantee or removal or resignation of the Trust Preferred Securities Guarantee
Trustee pursuant to this Section 4.2, the Guarantor shall pay to the Trust
Preferred Securities Guarantee Trustee all amounts due to the Trust Preferred
Securities Guarantee Trustee for fees and reimbursement of expenses which have
accrued to the date of such termination, removal or resignation.

                                    ARTICLE V
                                    GUARANTEE

SECTION 5.1    GUARANTEE

               The Guarantor irrevocably and unconditionally agrees to pay in
full to the Holders the Guarantee Payments (without duplication of amounts
theretofore paid by the Issuer), as and when due, regardless of any defense,
right of set-off or counterclaim that the Issuer may have or assert. The
Guarantor's obligation to make a Guarantee Payment may be satisfied by direct
payment of the required amounts by the Guarantor to the Holders or by causing
the Issuer to pay such amounts to the Holders.

SECTION 5.2    WAIVER OF NOTICE AND DEMAND

               The Guarantor hereby waives notice of acceptance of this Trust
Preferred Securities Guarantee and of any liability to which it applies or may
apply, presentment, demand for payment, any right to require a proceeding first
against the Issuer or any other Person before proceeding against the Guarantor,
protest, notice of nonpayment, notice of dishonor, notice of redemption and all
other notices and demands.

SECTION 5.3    OBLIGATIONS NOT AFFECTED

               The obligations, covenants, agreements and duties of the
Guarantor under this Trust Preferred Securities Guarantee shall be absolute and
unconditional and shall remain in full force and effect until the entire
liquidation amount of all Trust Preferred Securities shall have been paid and
such obligations, covenants, agreements and duties shall in no way be affected
or impaired by reason of the happening from time to time of any event, including
without limitation the following, whether or not with notice to, or the consent
of, the Guarantor:

               (a)  the release or waiver, by operation of law or otherwise, of
the performance or observance by the Issuer of any express or implied agreement,
covenant, term or condition relating to the Trust Preferred Securities to be
performed or observed by the Issuer;

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               (b)  the extension of time for the payment by the Issuer of all
or any portion of the Distributions, Redemption Price, Liquidation Distribution
(as defined in the Declaration) or any other sums payable under the terms of the
Trust Preferred Securities or the extension of time for the performance of any
other obligation under, arising out of, or in connection with, the Trust
Preferred Securities (other than an extension of time for payment of
Distributions, Redemption Price, Liquidation Distribution or other sum payable
that results from the extension of any interest payment period on the Debentures
permitted by the Indenture);

               (c)  any failure, omission, delay or lack of diligence on the
part of the Property Trustee or the Holders to enforce, assert or exercise any
right, privilege, power or remedy conferred on the Property Trustee or the
Holders pursuant to the terms of the Trust Preferred Securities, or any action
on the part of the Issuer granting indulgence or extension of any kind;

               (d)  the voluntary or involuntary liquidation, dissolution, sale
of any collateral, receivership, insolvency, bankruptcy, assignment for the
benefit of creditors, reorganization, arrangement, composition or readjustment
of debt of, or other similar proceedings affecting, the Issuer or any of the
assets of the Issuer;

               (e)  any invalidity of, or defect or deficiency in, the Trust
Preferred Securities;

               (f)  the settlement or compromise of any obligation guaranteed
hereby or hereby incurred;

               (g)  any other circumstance whatsoever that might otherwise
constitute a legal or equitable discharge or defense of a guarantor, it being
the intent of this Section 5.3 that the obligations of the Guarantor with
respect to the Guarantee Payments shall be absolute and unconditional under any
and all circumstances.

               There shall be no obligation of the Holders to give notice to, or
obtain consent of, the Guarantor with respect to the happening of any of the
foregoing. No set-off, counterclaim, reduction or diminution of any obligation,
or any defense of any kind or nature that the Guarantor has or may have against
any Holder shall be available hereunder to the Guarantor against such Holder to
reduce the payments to it under this Trust Preferred Securities Guarantee.

SECTION 5.4    RIGHTS OF HOLDERS

               (a)  The Holders of a Majority in liquidation amount of the Trust
Preferred Securities have the right to direct the time, method and place of
conducting any proceeding for any remedy available to the Trust Preferred
Securities Guarantee Trustee in respect of this Trust Preferred Securities
Guarantee or exercising any trust or power conferred upon the Trust Preferred
Securities Guarantee Trustee under this Trust Preferred Securities Guarantee.

               (b)  If the Trust Preferred Securities Guarantee Trustee fails to
enforce such Trust Preferred Securities Guarantee, any Holder may institute a
legal proceeding directly against the Guarantor to enforce the Trust Preferred
Securities Guarantee Trustee's rights under this Trust Preferred Securities
Guarantee, without first instituting a legal proceeding against the

                                       14
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Issuer, the Trust Preferred Securities Guarantee Trustee or any other Person or
entity. Notwithstanding the foregoing, if the Guarantor has failed to make a
Guarantee Payment, a Holder may directly institute a proceeding against the
Guarantor for enforcement of the Trust Preferred Securities Guarantee for such
payment to the Holder of the principal of or interest on the Debentures on or
after the respective due dates specified in the Debentures, and the amount of
the payment will be based on the Holder's pro rata share of the amount due and
owing on all of the Trust Preferred Securities. The Guarantor waives any right
or remedy to require that any action be brought first against the Issuer or any
other Person or entity before proceeding directly against the Guarantor.

SECTION 5.5    GUARANTEE OF PAYMENT

               This Trust Preferred Securities Guarantee creates a guarantee of
payment and not of collection.

SECTION 5.6    SUBROGATION

               The Guarantor shall be subrogated to all (if any) rights of the
Holders against the Issuer in respect of any amounts paid to such Holders by the
Guarantor under this Trust Preferred Securities Guarantee; provided, however,
that the Guarantor shall not (except to the extent required by mandatory
provisions of law) be entitled to enforce or exercise any right that it may
acquire by way of subrogation or any indemnity, reimbursement or other
agreement, in all cases as a result of payment under this Trust Preferred
Securities Guarantee, if, at the time of any such payment, any amounts are due
and unpaid under this Trust Preferred Securities Guarantee. If any amount shall
be paid to the Guarantor in violation of the preceding sentence, the Guarantor
agrees to hold such amount in trust for the Holders and to pay over such amount
to the Holders.

SECTION 5.7    INDEPENDENT OBLIGATIONS

               The Guarantor acknowledges that its obligations hereunder are
independent of the obligations of the Issuer with respect to the Trust Preferred
Securities, and that the Guarantor shall be liable as principal and as debtor
hereunder to make Guarantee Payments pursuant to the terms of this Trust
Preferred Securities Guarantee notwithstanding the occurrence of any event
referred to in subsections (a) through (g), inclusive, of Section 5.3 hereof.

                                   ARTICLE VI
                    LIMITATION OF TRANSACTIONS; SUBORDINATION

SECTION 6.1    LIMITATION OF TRANSACTIONS

               So long as any Trust Preferred Securities remain outstanding, if
there shall have occurred a Guarantee Event of Default or an Event of Default,
or an event that, with the giving of notice or the lapse of time, or both, would
be a Guarantee Event of Default or an Event of Default then, prior to the
payment of all accrued interest on outstanding Debentures , the Guarantor shall
not (i) declare or pay any dividends or distributions on, or redeem, purchase,

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acquire, or make a liquidation payment with respect to, any of the Guarantor's
capital stock (which includes common and preferred stock), (ii) make any payment
of principal, interest or premium, if any, on or repay or repurchase or redeem
any debt securities of the Guarantor (including any Other Debentures) that rank
pari passu with or junior in right of payment to the Debentures or (iii) make
any guarantee payments with respect to any guarantee by the Guarantor of the
debt securities of any Subsidiary (including under Other Guarantees) if such
guarantee ranks equal or junior in right of payment to the Debentures (other
than (a) dividends or distributions in shares of, or options, warrants, rights
to subscribe for or purchase shares of, common stock of the Guarantor, (b) any
declaration of a dividend in connection with the implementation of a
stockholders' rights plan, or the issuance of stock under any such plan in the
future, or the redemption or repurchase of any such rights pursuant thereto, (c)
payments under the Trust Preferred Securities Guarantee, (d) the purchase of
fractional shares resulting from a reclassification of the Guarantor's capital
stock, (e) the purchase of fractional interests in shares of the Guarantor's
capital stock pursuant to the conversion or exchange provisions of such capital
stock or the security being converted or exchanged and (f) purchases of common
stock related to the issuance of common stock or rights under any of the
Guarantor's benefit plans for its directors, officers or employees or any of the
Guarantor's dividend reinvestment plans).

SECTION 6.2    RANKING

               This Trust Preferred Securities Guarantee will constitute an
unsecured obligation of the Guarantor and will rank (i) subordinate and junior
in right of payment to Senior and Subordinated Indebtedness (as defined in the
Indenture), to the same extent and in the same manner that the Debentures are
subordinated to Senior and Subordinated Indebtedness pursuant to the Indenture,
(ii) pari passu with the Debentures, the Other Debentures, the Common Securities
Guarantee, any Other Guarantee and any Other Common Securities Guarantee, (iii)
senior to the Guarantor's capital stock and (iv) effectively subordinated to the
liabilities and obligations of the Guarantor's subsidiaries. If an Event of
Default has occurred and is continuing, the rights of the holders of the Common
Securities to receive any payments shall be subordinated to the rights of the
Holders to receive Guarantee Payments hereunder.

                                   ARTICLE VII
                                   TERMINATION

SECTION 7.1    TERMINATION

               This Trust Preferred Securities Guarantee shall terminate (i)
upon full payment of the Redemption Price (as defined in the Declaration) of all
Trust Preferred Securities or (ii) upon liquidation of the Issuer and the full
payment of the amounts payable in accordance with the Declaration or the
distribution of the Debentures to the Holders and the holders of Common
Securities. Notwithstanding the foregoing, this Trust Preferred Securities
Guarantee will continue to be effective or will be reinstated, as the case may
be, if at any time any Holder must restore payment of any sums paid under the
Trust Preferred Securities or under this Trust Preferred Securities Guarantee.

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                                  ARTICLE VIII
                                 INDEMNIFICATION

SECTION 8.1    EXCULPATION

               (a)  No Indemnified Person shall be liable, responsible or
accountable in damages or otherwise to the Guarantor or any Covered Person for
any loss, damage or claim incurred by reason of any act or omission performed or
omitted by such Indemnified Person in good faith in accordance with this Trust
Preferred Securities Guarantee and in a manner that such Indemnified Person
reasonably believed to be within the scope of the authority conferred on such
Indemnified Person by this Trust Preferred Securities Guarantee or by law,
except that an Indemnified Person shall be liable for any such loss, damage or
claim incurred by reason of such Indemnified Person's negligence or willful
misconduct with respect to such acts or omissions.

               (b)  An Indemnified Person shall be fully protected in relying in
good faith upon the records of the Guarantor and upon such information,
opinions, reports or statements presented to the Guarantor by any Person as to
matters the Indemnified Person reasonably believes are within such other
Person's professional or expert competence and who has been selected with
reasonable care by or on behalf of the Guarantor, including information,
opinions, reports or statements as to the value and amount of the assets,
liabilities, profits, losses, or any other facts pertinent to the existence and
amount of assets from which Distributions to Holders might properly be paid.

SECTION 8.2    INDEMNIFICATION

               The Guarantor agrees to indemnify each Indemnified Person for,
and to hold each Indemnified Person harmless against, any and all loss,
liability, damage, claim or expense incurred without negligence or bad faith on
its part, arising out of or in connection with the acceptance or administration
of the trust or trusts hereunder, including the costs and expenses (including
reasonable legal fees and expenses) of defending itself against, or
investigating, any claim or liability in connection with the exercise or
performance of any of its powers or duties hereunder. The obligation to
indemnify as set forth in this Section 8.2 shall survive the termination of this
Trust Preferred Securities Guarantee.

                                   ARTICLE IX
                                  MISCELLANEOUS

SECTION 9.1    SUCCESSORS AND ASSIGNS

               All guarantees and agreements contained in this Trust Preferred
Securities Guarantee shall bind the successors, assigns, receivers, trustees and
representatives of the Guarantor and shall inure to the benefit of the Holders
then outstanding.

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SECTION 9.2    AMENDMENTS

               Except with respect to any changes that do not adversely affect
the rights of Holders (in which case no consent of Holders will be required),
this Trust Preferred Securities Guarantee may only be amended with the prior
approval of the Holders of a Majority in liquidation amount of the Trust
Preferred Securities (including the stated amount that would be paid on
redemption, liquidation or otherwise, plus accrued and unpaid Distributions to
the date upon which the voting percentages are determined). The provisions of
the Declaration with respect to consents to amendments thereof (whether at a
meeting or otherwise) shall apply to the giving of such approval.

               Prior to executing any amendment hereto, the Trust Preferred
Securities Guarantee Trustee shall be entitled to receive and rely upon an
Opinion of Counsel stating that the execution of such amendment is authorized or
permitted by this Trust Preferred Securities Guarantee Agreement.

SECTION 9.3    NOTICES

               All notices provided for in this Trust Preferred Securities
Guarantee shall be in writing, duly signed by the party giving such notice, and
shall be delivered, telecopied or mailed by first class mail, as follows:

               (a)  If given to the Issuer, in care of the Trustee at the
Issuer's mailing address set forth below (or such other address as the Issuer
may give notice of to the Holders and the Trust Preferred Securities Guarantee
Trustee):

                              Coastal Capital Trust I
                              c/o Coastal Bancorp, Inc.
                              5718 Westheimer, Suite 600
                              Houston, Texas 77057
                              Attention:  Administrative Trustee
                              Telecopy:   (713) 435-5106

               (b)  If given to the Trust Preferred Securities Guarantee
Trustee, at the Trust Preferred Securities Guarantee Trustee's mailing address
set forth below (or such other address as the Trust Preferred Securities
Guarantee Trustee may give notice of to the Holders, the Guarantor and the
Issuer):

                              The Bank of New York
                              5 Penn Plaza
                              13th Floor
                              New York, New York  10001
                              Attention:  Corporate Trust Trustee Administration
                              Telecopy:   (212) ____-______

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               (c)  If given to the Guarantor, at the Guarantor's mailing
address set forth below (or such other address as the Guarantor may give notice
of to the Holders and the Trust Preferred Securities Guarantee Trustee):

                              Coastal Bancorp, Inc.
                              5718 Westheimer, Suite 600
                              Houston, Texas 77057
                              Attention:  Catherine N. Wylie
                                          Senior Executive Vice President and
                                          Chief Financial Officer
                              Telecopy:   (713) 435-5106

               (d)  If given to any Holder, at the address set forth on the
books and records of the Issuer.

               All such notices shall be deemed to have been given when received
in person, telecopied with receipt confirmed, or mailed by first class mail,
postage prepaid except that if a notice or other document is refused delivery or
cannot be delivered because of a changed address of which no notice was given,
such notice or other document shall be deemed to have been delivered on the date
of such refusal or inability to deliver.

SECTION 9.4    BENEFIT

               This Trust Preferred Securities Guarantee is solely for the
benefit of the Holders and, subject to Section 3.1(a), is not separately
transferable from the Trust Preferred Securities.

SECTION 9.5    GOVERNING LAW

               THIS TRUST PREFERRED SECURITIES GUARANTEE SHALL BE GOVERNED BY,
AND CONSTRUED AND INTERPRETED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW
YORK, WITHOUT REGARD TO CONFLICTS OF LAWS PRINCIPLES THEREOF.

                                       19
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               THIS TRUST PREFERRED SECURITIES GUARANTEE is executed as of the
day and year first above written.

                                    COASTAL BANCORP, INC., as Guarantor

                                    By:
                                        --------------------------------------
                                        Catherine N. Wylie
                                        Senior Executive Vice President and
                                        Chief Financial Officer

                                    THE BANK OF NEW YORK, as Trust Preferred
                                       Securities Guarantee Trustee

                                    By:
                                        --------------------------------------
                                        Name:
                                        Title:

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