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                                                                Exhibit 10(rr)

                               GUARANTY AGREEMENT

         THIS GUARANTY AGREEMENT, dated as of February 14, 2002 (this "Guaranty
Agreement"), is made by TXU Corp., a Texas corporation (together with its
successors and assigns, including Surviving Entities pursuant to Section 9(b)
and Replacement Guarantors pursuant to Section 21, the "Guarantor"), in favor of
State Street Bank and Trust Company of Connecticut, National Association, as
Owner Trustee of the ZSF/Dallas Tower Trust, a Delaware grantor trust (in such
capacity, together with its successors and assigns, the "Lessor"). Capitalized
terms used herein have the meanings ascribed to such terms in Section 22
(including the incorporation of the definitions of terms that are defined in the
Lease, as defined below), unless otherwise defined elsewhere herein.

         WHEREAS, Lessor and TXU Properties Company, a Texas corporation
(together with its successors and permitted assigns, "Lessee"), have entered
into that certain Lease Agreement dated as of even date herewith (as amended,
restated, supplemented or otherwise modified from time to time, the "Lease");
and

         WHEREAS, Lessor, LaSalle Bank National Association, as Indenture
Trustee (in such capacity, together with its successors and assigns, the
"Indenture Trustee"), and First Union National Bank, as Servicer (in such
capacity, together with its successors and assigns, the "Servicer"), are parties
to that certain Indenture and Servicing Agreement dated as of even date herewith
(as amended, restated, supplemented or otherwise modified from time to time, the
"Indenture"); and

         WHEREAS, in connection with the transactions contemplated by the
Indenture, LaSalle Bank National Association, as Pass-Through Trustee for the
benefit of the Certificateholders (as defined below)(in such capacity, together
with its successors and assigns, the "Pass-Through Trustee"), has executed and
delivered that certain Declaration of Trust dated as of even date herewith (as
amended, restated, supplemented or otherwise modified from time to time, the
"Declaration of Trust") pursuant to which the Energy Plaza Lease Pass-Through
Trust, a Delaware grantor trust (the "Trust") was created; and

         WHEREAS, pursuant to the Assignment of Agreements (as defined in the
Indenture) and the Assignment of Lease (as defined in the Indenture), Lessor
shall assign to the Indenture Trustee for the benefit of the registered holders
from time to time of the Secured Notes (the "Holders"), and for the benefit of
the registered holders from time to time (the "Certificateholders") of the Trust
Certificates issued pursuant to the Declaration of Trust (the "Certificates"),
all of its rights, titles, and interests in and to this Guaranty Agreement, the
Lease, and the other Lease Operative Documents (other than the Excepted Payments
and the Excepted Rights) substantially contemporaneous with the execution and
delivery hereof; and

         WHEREAS, it is a condition to the effectiveness of the Lease that this
Guaranty Agreement shall have been executed and delivered by the Guarantor and
shall be in full force and effect;
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         NOW THEREFORE, in order to induce, and in consideration of, the
execution and delivery of the Lease, the Guarantor hereby covenants and agrees
with, and represents and warrants to Lessor for the benefit of each of the
Lessor, the Servicer, the Trust, the Pass-Through Trustee, each other Holder,
each Certificateholder, each Indemnitee, each member of each Indemnitee's Group,
each Tax Indemnitee and each other Person to whom Base Rent or Supplemental Rent
may be payable pursuant to the Lease (together with all successors and assigns
of the foregoing, collectively, the "Beneficiaries," and each individually, a
"Beneficiary") as follows:

1.       THE GUARANTY. The Guarantor hereby irrevocably and unconditionally
         guarantees to each Beneficiary to which such obligations are owing the
         following obligations:

                (i) the due, punctual and full payment by the Lessee (whether
         at the stated time for payment thereof,  by demand or otherwise) of
         all  amounts to be paid by the  Lessee  pursuant  to the Lease and the
         other  Lease  Operative  Documents,  including  but not limited to Base
         Rent, Supplemental Rent, amounts payable by Lessee if Lessee
         self-insures  pursuant to Section 9.1(g) of the Lease,  amounts payable
         by Lessee pursuant to Sections 19.1 and 19.2 of the Lease (and other
         similar  provisions of the other Lease Operative Documents), the
         purchase  price of the  Property if Lessee exercises its right to
         purchase  the Property pursuant to the Lease, any applicable
         Make-Whole Premium,  any Termination Value Payment, any Stipulated
         Loss Value Payment, any late charges or penalties, interest payable on
         late charges or penalties,  all amounts payable by Lessee under
         Article 17 of the Lease (including but not limited to liquidated
         damages),  fees,  expenses (including but not limited to the reasonable
         fees and expenses of attorneys, accountants, experts, and advisors),
         or other similar costs  (including  all such amounts which would become
         due but for the  operation of the automatic stay under Section 362(a)
         of the United  States  Bankruptcy Code, 11 U.S.C.ss.362(a), and the
         operation of Sections 502(b) and 506(b) of the United  States
         Bankruptcy  Code, 11 U.S.C. ss.502(b) andss.506(b)); and

                (ii) the due, prompt and faithful performance of, and compliance
         with, all other obligations, covenants, terms, conditions and
         undertakings of the Lessee contained in each Lease Operative Document
         to which Lessee is a party in accordance with the terms thereof (all
         such obligations described in clauses (i) and (ii) above are herein
         called the "Guaranteed Obligations").

         The guaranty in the preceding sentence is an absolute, present and
         continuing guaranty of payment and not of collectability and is in no
         way conditional or contingent upon any attempt to collect from Lessee
         or any other Person or upon any other action, occurrence or
         circumstance whatsoever. In the event that the Lessee shall fail so to
         pay any of such Guaranteed Obligations, the Guarantor agrees to pay the
         same when due to each Beneficiary, without demand, presentment, protest
         or notice of any kind. Each default under any Lease Operative Document
         shall give rise to a separate cause of action hereunder and separate
         suits may be brought hereunder as each cause of action arises.

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         The Guarantor also hereby agrees to pay and to indemnify and save each
         Beneficiary harmless from and against any damage, loss, cost or expense
         (including but not limited to the reasonable fees and expenses of
         attorneys, accountants, and advisors) which such Beneficiary may incur
         or be subject to as a consequence, direct or indirect, of (i) any
         breach by the Guarantor or Lessee of any covenant, term or condition
         in, or the occurrence of any default under, this Guaranty Agreement or
         any other Lease Operative Document, together with all expenses
         resulting from the compromise or defense of any claims or liabilities
         arising as a result of any such breach or default, and (ii) any legal
         action threatened or commenced in connection with or relating to this
         Guaranty Agreement or any other Lease Operative Document.

2.       OBLIGATIONS ABSOLUTE.  The obligations of the Guarantor hereunder shall
         be primary,  absolute,  irrevocable and unconditional,irrespective of
         the validity,  regularity or enforceability of any of the Indenture,
         the Lease, or any of the other Operative Documents (collectively,  the
         "Transaction  Documents"), shall not be subject to any counterclaim,
         setoff,  deduction  or defense based upon any claim the Guarantor may
         have against the Lessee,  any  Beneficiary, or otherwise, and shall
         remain in full force and effect without regard to, and (subject to the
         provisions of Section 21 hereof with respect to the release of
         the Guarantor upon the substitution of a Replacement Guarantor
         hereunder)  shall not be released,  discharged or in any way
         affected by, any  circumstance  or  condition  whatsoever  (whether or
         not the  Guarantor  shall have any  knowledge or notice thereof),
         including, without limitation: (a) any amendment,  restatement,
         supplement or other modification from time to time to or of the
         Transaction  Documents or any other instrument referred to therein
         (except that the obligations of the Guarantor hereunder shall apply to
         the  Transaction  Documents or such other instruments as so amended,
         restated, supplemented or modified) or any assignment or transfer of
         any thereof or of any interest therein, or any furnishing, acceptance
         or release of any security for the Guaranteed  Obligations,  (b) any
         waiver, consent,  extension,  indulgence or other action or inaction
         under or in respect of the Transaction Documents; (c) any bankruptcy,
         insolvency,  readjustment,  composition,  liquidation or similar
         proceeding with respect to the Lessor, the owner participant in the
         Lessor, the Pass-Through Trustee, or the Lessee or its property; (d)any
         merger, amalgamation or consolidation of the Guarantor,  the Lessor,
         the Pass-Through  Trustee, or the Lessee into or with any other Person
         or any sale, lease or transfer of any or all of the assets of the
         Guarantor,  the Lessor,  the Pass-Through  Trustee,  or the Lessee to
         any Person; (e) any failure on the part of the Lessor, the Pass-Through
         Trustee, or the Lessee for any reason to comply with or perform any of
         the terms of any other  agreement  with the Guarantor; or (f) any other
         circumstance which might otherwise constitute a legal or equitable
         discharge or defense of a guarantor.  The Guarantor covenants that its
         obligations hereunder will not be discharged except by payment in full
         of all of the Guaranteed Obligations.

3.       WAIVER.  The Guarantor unconditionally waives to the fullest extent
         permitted by law, (a) notice of acceptance  hereof,  of any action
         taken or omitted in reliance  hereon and of any defaults by the Lessee
         in the payment of any amounts due under the Transaction  Documents,
         and of any of the matters  referred to in Section 2 hereof,  (b) all
         notices which may be required by statute, rule of law or otherwise to
         preserve any of the rights of any Beneficiary against the Guarantor,
         including, without limitation, presentment to or

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         demand for payment from the Lessee or the  Guarantor,  notice to the
         Lessee or to the Guarantor of default or protest for  nonpayment or
         dishonor and the filing of claims with a court in the event of the
         bankruptcy of the Lessee, the Lessor, the owner  participant  in the
         Lessor or the  Pass-Through  Trustee, (c) any right to the enforcement,
         assertion or exercise by any  Beneficiary  of any right,  power or
         remedy  conferred in this  Guaranty  Agreement or the other
         Transaction  Documents,  (d) any  requirement or diligence on the part
         of any Beneficiary and (e) any other act or omission or thing or delay
         to do any other act or thing  which  might in any manner or to any
         extent vary the risk of the  Guarantor or which might otherwise
         operate as a discharge of the Guarantor.

4.       OBLIGATIONS  UNIMPAIRED.  The Guarantor  authorizes  each  Beneficiary,
         without notice or demand to the Guarantor and without affecting its
         obligations hereunder, from time to time (a) to renew, compromise,
         extend,  accelerate or otherwise change the time for payment of, or
         otherwise change the terms of, all or any part of the Guaranteed
         Obligations  and the  Transaction Documents or any other instrument
         referred  to therein,  (b) to take and hold security for the payment
         of the Guaranteed Obligations, for the performance of the Transaction
         Documents, for the performance of this Guaranty Agreement or otherwise
         for the indebtedness guaranteed hereby and to exchange, enforce, waive
         and  release  any such  security,  (c) to obtain additional or
         substitute  endorsers or guarantors; (d) to exercise or refrain from
         exercising any rights against the Lessee, the Lessor, the Pass-Through
         Trustee, and others; and (e) to apply any sums, by whomsoever paid or
         however realized,  to the payment of any  Guaranteed  Obligation
         hereunder.  The Guarantor waives any right to require any Beneficiary
         to proceed against any  additional  or substitute endorsers or
         guarantors or to pursue or exhaust any security provided by the Lessee,
         the Lessor,  the Pass-Through Trustee,  the Guarantor or any other
         Person or to pursue any other remedy available to any Beneficiary.

5.       SUBROGATION. The Guarantor will not exercise against the Lessee, any
         Additional Guarantor (as defined in Section 9(c)(i) ) or any party
         obligated under any Qualified Letter of Credit (as defined in Section
         9(c)(iv) ), any rights that it may have acquired by way of subrogation
         under this Guaranty Agreement, by any payment made hereunder or
         otherwise, or accept any payment on account of such subrogation rights,
         or any rights of reimbursement or indemnity or any rights or recourse
         to any security for the Guaranteed Obligations unless and until all of
         the obligations, undertakings or conditions to be performed or observed
         by the Lessee pursuant to the Lease and by the Lessee and the Guarantor
         pursuant to the other Transaction Documents at the time of the
         Guarantor's exercise of any such right shall have been performed,
         observed or paid in full.

         For a period of one year after the payment in full of the Guaranteed
         Obligations, the Guarantor hereby waives (x) all rights of subrogation
         which it may at any time otherwise have as a result of this Guaranty
         Agreement (whether statutory or otherwise) to the claims of the Lessor
         and the other Beneficiaries against the Lessee or any other guarantor
         of the Guaranteed Obligations (each referred to herein as the "Other
         Party") and all contractual, statutory or common law rights of
         reimbursement, contribution or indemnity from any Other Party which it
         may at any time otherwise have as a result of this Guaranty Agreement;
         (y) any right to enforce any other remedy which the Lessor and the
         other Beneficiaries now have or may hereafter have against any Other
         Party; and (z) all claims (as such term is defined in the Bankruptcy
         Code) it may at any time otherwise have against any Other Party arising
         from any transaction whatsoever, including without limitation its right
         to assert or enforce any such claims.

                                       4
<PAGE>

6.       REINSTATEMENT OF GUARANTY.  This Guaranty Agreement shall continue to
         be effective,  or be reinstated,  as the case may be, if and to the
         extent at any time payment, in whole or in part, of any of the sums
         due to any Beneficiary  under the Lease or any other sum constituting
         any of the other Guaranteed Obligations is rescinded or must otherwise
         be restored or returned by any Beneficiary upon the insolvency,
         bankruptcy, dissolution, liquidation or reorganization of the Lessee,
         the Lessor, the owner participant in the Lessor, or the Pass-Through
         Trustee,  or upon or as a result of the appointment of a custodian,
         receiver, trustee  or other officer with similar powers with respect to
         the  Lessee, the Lessor, such owner participant,  the Pass-Through
         Trustee or any  substantial  part of any  property of any of the
         foregoing,  or  otherwise,  all as though such payments had not been
         made.  If an event  permitting  Lessor  or any  other  Beneficiary  to
         demand  payment  of any of the Guaranteed  Obligations  shall at any
         time have occurred and be continuing and such demand shall at such
         time be prevented or the right of any Beneficiary to receive any
         payment under any  Transaction Document shall at such time be delayed
         or otherwise affected by reason of the pendency against the Lessee of
         a case or proceeding under a bankruptcy or insolvency law, the
         Guarantor agrees that, for purposes of this Guaranty Agreement and its
         obligations  hereunder,  such Guaranteed Obligation shall be deemed to
         have been demanded with the same effect as if Lessor or such other
         Beneficiary had demanded the same in  accordance with the terms of the
         Transaction  Documents, and the Guarantor shall forthwith pay such
         demanded amount and any other amounts guaranteed hereunder.

7.       PAYMENTS.  The Guarantor hereby guarantees that the Guaranteed
         Obligations  will be paid to the  Beneficiaries  in lawful
         currency  of the United  States of America  and in  immediately
         available  funds,  at the times and places  provided  in, and
         otherwise strictly in accordance with the terms and provisions of, the
         applicable  Transaction  Documents giving rise to such Guaranteed
         Obligations (regardless of any law, regulation or decree now or
         hereafter in effect which might in any manner affect the Guaranteed
         Obligations,  or the rights of any such  Beneficiary  with respect
         thereto as against the Lessee,  or cause or permit to be invoked any
         alteration in the time, amount or manner of  payment by the Lessee of
         any or all of the Guaranteed  Obligations), without set-off or
         counterclaim and free and clear of, and without reduction for or on
         account of, any present or future income, stamp or other taxes, levies,
         imposts,  duties,  charges,  fees, deductions or withholdings now
         or hereafter  imposed,  levied,  collected,  withheld or assessed by
         any country (or by any  political  subdivision  or taxing
         authority  thereof or therein) excluding taxes and other amounts for
         which the Lessee has no  obligation to pay pursuant to the Lease or the
         other Lease Operative Documents (such  non-excluded taxes and other
         amounts being called  "Taxes").  If any Taxes are required to be
         withheld for any amount payable to any Beneficiary under this Guaranty
         Agreement,  the amounts so payable to the applicable Beneficiary shall
         be increased to the extent necessary to yield to such Beneficiary
         (after payment of all Taxes) interest or any such other amounts at the
         rates or in the amounts specified in the Transaction Documents.

                                       5
<PAGE>

8.       RANK OF GUARANTY. The Guarantor agrees that its
         obligations under this Guaranty Agreement shall rank
         at least pari passu with all other unsecured senior
         obligations of the Guarantor now or hereafter
         existing.

9.       ADDITIONAL COVENANTS OF THE GUARANTOR.

(a)      General. So long as the Guaranteed Obligations are
         outstanding or the Transaction Documents shall remain
         in effect, the Guarantor agrees that, unless the
         Majority" in Interest of the Certificateholders
         otherwise consents in writing:

(i)      Maintenance  of Corporate  Existence,  Etc. Subject to Section 9(b),
         -------------------------------------------
         the Guarantor  will at all times do or cause to be done all things
         necessary to maintain and preserve its corporate existence, and
         maintain,  preserve and renew its and its Subsidiaries' licenses,
         patents and franchises material  to the conduct of the business of the
         Guarantor and such Subsidiaries taken as a whole, provided that nothing
         contained in this Section 9(a)(i) shall (A) require the Guarantor or
         any such Subsidiary to maintain, preserve or renew any license, patent
         or franchise not necessary or desirable in the conduct of its business,
         or (B) prohibit the Guarantor from terminating the corporate existence
         of a Subsidiary (other than the Lessee, in which case the provisions of
         the Lease relating to the termination of the corporate existence of the
         Lessee shall apply) if in the reasonable opinion of the Guarantor such
         termination is in the best interests of the Guarantor and is not
         disadvantageous to any Beneficiary.

(ii)     Financial Statements. Etc. The Guarantor will furnish
         -------------------------
         to the Lessor and to each Certificateholder, as
         applicable:

                (A) as soon as publicly available, and in any event within the
         earlier of (1) 120 days after the end of each fiscal year of the
         Guarantor  or (2) the date by which the annual financial statements of
         the Guarantor are required to be delivered pursuant to its primary
         revolving credit facility,  a consolidated  balance sheet of the
         Guarantor and its consolidated  Subsidiaries as at the end of such
         fiscal year and the related consolidated statements of operations and
         sources of funds of the Guarantor and its consolidated  Subsidiaries
         for such fiscal year, prepared in conformity with GAAP (except as
         disclosed in the notes thereto) and reported on by independent
         accountants of recognized national standing;  provided, that delivery
         of copies of the annual report on Form 10-K of the Guarantor for such
         annual period filed with the Securities and Exchange Commission shall
         be deemed to satisfy the requirements of this clause (A) with respect
         to consolidated financial statements if such financial statements are
         included in such report;

                (B) as soon as publicly available, and in any event within the
         earlier of (1) 60 days after the end of each quarter  (except the
         last  quarter)  of each  fiscal  year of the  Guarantor or (2) the
         date by which the quarterly


                                       6
<PAGE>

         financial statements of the Guarantor are required to be delivered
         pursuant to its primary revolving credit facility, a consolidated
         balance sheet of the Guarantor and its consolidated Subsidiaries
         as at the end of such quarter and the related consolidated statements
         of operations and sources of funds of the Guarantor and its
         consolidated Subsidiaries for such quarter and for the period from the
         beginning of such fiscal year to the end of such quarter, in each case
         setting forth  comparative figures for the related  periods in the
         prior fiscal year, certified by the chief financial officer, the chief
         accounting officer or the treasurer of the Guarantor to have been
         prepared in  accordance  with GAAP (except as disclosed in the notes
         thereto and subject to normal year-end adjustments); provided, that
         delivery of copies of the quarterly report on Form 10-Q of the
         Guarantor for such quarterly period filed with the Securities and
         Exchange Commission shall be deemed to satisfy the requirements of this
         clause (B) with respect to consolidated financial statements if such
         financial statements are included in such report;

                  (C) concurrently with the delivery each year of the financial
         statements furnished pursuant to Section 9(a)(ii)(A), an officer's
         certificate of the Guarantor certifying that the signer has reviewed,
         or caused to be reviewed by persons under his supervision, the relevant
         terms of this Guaranty Agreement and has made, or caused to be made
         under his supervision, a review of the transactions and financial
         condition of the Guarantor and its consolidated Subsidiaries during the
         preceding year, and that such review has not disclosed the existence
         during such period, nor does the signer have knowledge of the existence
         as at the date of such certificate, of a Lease Default, a Lease Event
         of Default or a default hereunder, or of any other default with respect
         to the Guaranteed Obligations or, if any such a default existed or
         exists, specifying the nature and period of existence thereof and what
         action the Guarantor has taken or is taking or proposed to take with
         respect thereto;

                  (D) with reasonable promptness, such other information
         relating to the Guarantor, any of its Material Subsidiaries, or the
         Lessee that any Certificateholder may from time to time reasonably
         request and that the Guarantor may furnish without violating applicable
         securities laws (taking into account the Certificateholders'
         confidentiality obligations under paragraph 9D of the Certificate
         Purchase Agreement pursuant to which the Certificates are being
         issued); and

                  (E) upon the request of any Certificateholder,  provide such
         Certificateholder, and any qualified institutional buyer designated
         by such Certificateholder, such financial and other information as such
         Certificateholder may reasonably determine to be necessary in order to
         permit compliance with the information requirements of Rule 144A (as
         such term is defined in the  Indenture) in connection with the resale
         of the Trust  Certificates (as such term is defined in the Indenture),
         except at such


                                       7
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         times as the Guarantor is subject to the reporting
         requirements  of section 13 or 15(d) of the Exchange Act (as such term
         is defined in the Indenture) (for the purpose of this clause (E), the
         term "qualified institutional buyer" shall have the meaning specified
         in Rule 144A).

         (iii) Inspections, Etc. The Guarantor will permit any
         authorized representative of Lessor or any
         Certificateholder, upon reasonable prior notice and
         at the expense of the Guarantor at such times as a
         Lease Default or a Lease Event of Default shall exist
         and otherwise at the expense of the Lessor or such
         Certificateholder, as the case may be, to visit and
         discuss with the Guarantor's officers the financial
         condition of the Guarantor and the Guarantor's
         ability to comply with its obligations hereunder, all
         at such reasonable times and intervals as Lessor or
         such Certificateholder may request.

         (b) Merger, Consolidation. The Guarantor shall not consolidate
with, or merge with or into, any other Person or convey, transfer or
lease all or substantially all of its assets as an entirety (whether by
one transaction or a series of related transactions) to any Person,
unless each of the following conditions shall be satisfied:

                 (i) the successor entity formed by such consolidation,
                 the survivor of such merger (including the Guarantor)
                 or the successor entity which acquires by conveyance,
                 transfer or lease all or substantially all of the
                 assets of the Guarantor as an entirety (each of the
                 foregoing being referred to as the "Surviving
                 Entity") shall be a Solvent entity organized and
                 existing under the laws of the United States of
                 America, any State thereof or the District of
                 Columbia and at least $5,000,000,000 of the Surviving
                 Entity's consolidated assets shall be within the
                 United States;

                 (ii) the Surviving Entity (if not the Guarantor), shall
                 expressly assume in writing by instrument or instruments
                 reasonably satisfactory to the Majority in Interest of the
                 Certificateholders, in scope, form and legal effect, the due
                 and punctual payment, performance and observance of all
                 obligations of the Guarantor under this Guaranty Agreement,
                 with the same effect as if such entity had originally been
                 named Guarantor herein or had been a party hereto;

                 (iii) prior to and immediately after giving effect to such
                 transaction, no Lease Default or Lease Event of Default
                 shall exist;

                 (iv) the Surviving Entity shall have delivered to the
                 Lessor an officer's certificate stating that such
                 consolidation, merger, conveyance, transfer or lease
                 and the assumption agreement required by clause (ii)
                 above comply with the provisions of this Section 9(b);

                 (v)(A) in the case of any consolidation, merger, conveyance,
                 transfer or lease with an entity  that is an Affiliate of the
                 Guarantor prior to giving effect to such transaction, then


                                       8
<PAGE>

                 immediately  after  giving  effect to such transaction the
                 tangible net worth (calculated in accordance  with GAAP) of
                 the Successor  Entity shall be equal to or greater than
                 $3,000,000,000, (B) in the case of any consolidation, merger,
                 conveyance, transfer or lease with any  Affiliate of the
                 Guarantor to which the  foregoing  subclause (A) does not
                 apply, the Guarantor shall have first obtained the prior
                 written consent of the Lessor and the Majority in Interest
                 of the Certificateholders, and (C) in the case of any
                 consolidation, merger, conveyance, transfer or lease with any
                 Person that is not an Affiliate of the Guarantor prior to
                 giving effect to such  transaction,either (1) the tangible
                 net worth (calculated in accordance with GAAP) of the
                 Surviving Entity immediately after giving effect to such
                 transaction shall be equal to or greater than the greater of
                 $3,000,000,000 and the tangible net worth (calculated in
                 accordance  with GAAP) of the Guarantor immediately prior to
                 such transaction or (2) the Guarantor shall have first
                 obtained the prior written  consent of the Lessor and the
                 Majority in Interest of the Certificateholders;

                 (vi)immediately after giving effect to such transaction,
                 the Surviving Entity shall have Acceptable Debt
                 ratings from Standard & Poor's and Moody's that in
                 each case are at least as high as the Debt Ratings of
                 the Guarantor immediately prior to the date of such
                 transaction; and

                 (vii)in the case of any such consolidation, merger,
                 conveyance, transfer or lease in which the Guarantor
                 is not the Surviving Entity, the Surviving Entity
                 shall have caused to be delivered to Lessor and the
                 Indenture Trustee an opinion of counsel reasonably
                 acceptable to the Majority in Interest of the
                 Certificateholders, to the effect that all agreements
                 or instruments effecting the assumption referred to
                 in clause (ii) above are enforceable in accordance
                 with their terms and comply with the terms of the
                 Transaction Documents.

                 Upon any consolidation or merger, or any conveyance,
          transfer or lease of all or substantially all of the assets of
          the Guarantor as an entirety, in accordance with this Section
          9(b), in a transaction in which the Guarantor is not the
          Surviving Entity, the Surviving Entity shall succeed to, and
          be substituted for, the Guarantor under this Guaranty Agreement,
          with the same effect as if such successor had been
          named as the Guarantor herein.

                  (c) Ratings Decline. If any Ratings Decline occurs, the
         Guarantor shall provide written notice thereof to the Lessor, the
         Indenture Trustee, the Servicer and each Certificateholder within 10
         days thereafter and shall cause an Additional Guaranty or a Qualified
         Letter of Credit satisfying the requirements set forth below to be
         provided to the Indenture Trustee (as assignee of the Lessor's rights
         under the Lease) within 30 days after such Ratings Decline. Any failure
         to provide such Additional Guaranty or Qualified Letter of Credit
         within such 30-day period shall constitute a Lease Event of Default. In
         the event that the Guarantor regains Acceptable Debt. Ratings, and
         provided that no Lease Default or Lease Event of Default shall exist at
         the time of either such notice or

                                       9
<PAGE>

         such release, the Guarantor may, upon at least thirty (30) days' prior
         written notice to the Lessor, the Indenture Trustee, the Servicer and
         each Certificateholder, obtain the release of such Additional Guaranty
         or Qualified Letter of Credit, as the case may be, by delivering to the
         Lessor, the Indenture Trustee, the Servicer and each Certificateholder
         satisfactory evidence that the Guarantor has regained Acceptable Debt
         Ratings. In the event of a Ratings Decline occurring after such
         release, the provisions of this Section 9(c) requiring the delivery of
         an Additional Guaranty or a Qualified Letter of Credit shall again
         apply. In addition, at any time that an Additional Guaranty or a
         Qualified Letter of Credit shall be in effect, the Guarantor may, upon
         at least thirty (30) days' prior written notice to the Lessor, the
         Indenture Trustee (as assignee of the Lessor's rights under the Lease),
         the Servicer and each Certificateholder, substitute an Additional
         Guaranty or a Qualified Letter of Credit for the Additional Guaranty or
         the Qualified Letter of Credit then outstanding pursuant hereto,
         provided that no Lease Default or  Lease Event of Default shall exist
         at the time of any such notice or substitution.

                 (i)  "Additional Guaranty" shall mean a guaranty agreement
                 that has been duly executed and delivered by an Acceptable
                 Guarantor (an "Additional Guarantor") and is in a form
                 substantially identical to this Guaranty Agreement (with
                 appropriate references revised to reflect the identity and
                 form of business organization of the Additional Guarantor but
                 with the deletion of Section 21 and references to a Replacement
                 Guarantor). Without limitation of the foregoing, any
                 Additional Guaranty shall include credit enhancement
                 requirements identical to those set forth in this Section 9(c)
                 to protect the Beneficiaries in the event a Ratings Decline
                 occurs with respect to any Debt Rating of such Additional
                 Guarantor.

                 (ii) "Acceptable Guarantor" shall mean a Solvent entity
                 organized and existing under the laws of the United States of
                 America, any State thereof or the District of Columbia that
                 satisfies all of the following criteria:

                        (A) at least 35% of such entity's consolidated assets,
                 properties and operations shall be within the United States;

                        (B) the tangible net worth (calculated in accordance
                 with GAAP from audited financial statements reasonably
                 acceptable to the Majority in Interest of Certificateholders
                 and provided to the Indenture Trustee, the Servicer and the
                 holders of the Trust Certificates prior the delivery of such
                 Additional Guaranty) of such entity must be equal to or greater
                 than $3,000,000,000; and

                        (C) such entity must have Acceptable Debt Ratings.

                 (iii) "Qualified Letter of Credit" shall mean an
                 uncollateralized, irrevocable, standby letter of credit issued
                 by an Acceptable Bank, in form and substance satisfactory to
                 the Majority in Interest of Certificateholders (in their sole
                 and exclusive judgment exercised in good faith), that
                 satisfies all of the following criteria:

                                       10
<PAGE>

                          (A) the Servicer, acting on behalf of the Indenture
                  Trustee, as assignee of the Lessor's rights under the
                  Lease, shall be the initial beneficiary of such letter of
                  credit;

                          (B) such letter of credit shall authorize the Servicer
                  to draw on the Issuing Bank from time to time immediately
                  available funds in an aggregate amount which at all times
                  shall be at least equal to the greater of (1) the aggregate
                  Base Rent remaining to be paid over the remainder of the
                  scheduled Base Term (determined initially on the date of the
                  issuance thereof without discounting) and (2) the largest
                  Stipulated Loss Value Payment payable by the Lessee
                  over the remainder of the scheduled Base Term;

                           (C) such letter of credit shall provide that it may
                  be drawn as provided in paragraph (vi) below, with each
                  drawing under this clause (C) or under the foregoing clause
                  (B) being made by presentation, at an office of the issuing
                  bank, in person, via courier or other delivery service, on or
                  before the stated expiry date thereof, of a certificate that
                  (I) identifies the letter of credit with respect to which such
                  certificate is being presented, (II) identifies the
                  event permitting such drawing and certifies that such
                  event has occurred, and (III) identifies the amount
                  being drawn thereunder;

                           (D) such letter of credit shall have a stated expiry
                  date which is at least one year from date of the issuance
                  thereof and, if such expiry date is prior to the end of the
                  Base Term,  which shall be automatically extended  pursuant to
                  the terms of such  letter of credit for a period of at least
                  one year from the date of such  expiration unless the issuer
                  thereof shall, not later than 30 days prior to the stated
                  expiry date, provide written notice to the Servicer, acting on
                  behalf of the Indenture Trustee (as assignee of the Lessor's
                  rights under the  Lease), in bold face type identifying such
                  letter of credit with particularity, stating that such notice
                  is a "Notice of Letter of Credit Expiration" and that such
                  letter of credit shall expire upon the expiry date stated in
                  such notice and in such letter of credit; and

                           (E) such letter of credit shall be transferable by
                  the beneficiary thereof in its entirety, without any fee
                  applicable to such transfer that is required to be
                  paid by any such transferor or transferee, to any
                  successor Servicer, acting on behalf of the Indenture
                  Trustee (as assignee of the Lessor's rights under the
                  Lease) pursuant to the terms of the Indenture.

        (iv)      "Acceptable Bank" shall mean any bank or trust
                  company (i) which is organized under the laws of the
                  United States of America or any State thereof, (ii)
                  which has capital, surplus and undivided profits
                  aggregating at least $1,000,000,000, and (iii) which
                  has a Debt Rating issued by Standard & Poor's of at
                  least of at least AA- and a Debt Rating issued by
                  Moody's of at least Aa3 (or such bank or trust
                  company must have either of such Debt Ratings in the


                                       11
<PAGE>

                  event that either Moody's or Standard & Poor's
                  (including their respective successors) shall have
                  ceased to exist).

          (v)     Any Additional Guaranty shall be delivered with (x)
                  legal opinions (in form and substance equivalent to
                  those opinions delivered with respect to this
                  Guaranty Agreement but consistent with the structure
                  of the Additional Guarantor), and (y) such
                  certificates, documents or instruments as the
                  Indenture Trustee, the Servicer or any
                  Certificateholder may reasonably request to provide
                  such Persons the types of legal opinions and such
                  certificates, documents or instruments it received
                  with respect to this Guaranty Agreement, each of
                  which deliveries shall be in form and substance
                  satisfactory to the Indenture Trustee, the Servicer
                  and each Certificateholder (in their sole and
                  exclusive judgments exercised in good faith).

          (vi)    With respect to any Qualified Letter of Credit, the
                  Servicer on behalf of the Indenture Trustee (as
                  assignee of the Lessor's rights under the Lease)
                  shall be permitted thereunder,

                        (A) from time to time, if the Lessee and the Guarantor
                  fail to make any payment of Base Rent on the applicable Rent
                  Payment Date, to draw upon such Qualified Letter of Credit in
                  an amount equal to the amount of Base Rent that is not paid on
                  such Rent Payment Date;

                        (B) if any event occurs that requires the Lessee to make
                  a Stipulated Loss Value Payment pursuant to the Lease and the
                  Lessee and the Guarantor fail to make such payment, to draw
                  upon such Qualified Letter of Credit in the amount of the
                  Stipulated Loss Value Payment calculated as of the business
                  day following the date of such occurrence;

                        (C) if any Lease Event of Default results in an
                  acceleration of the Base Rent payable under the Lease, to
                  draw upon such Qualified Letter of Credit in an amount equal
                  to the maximum remaining amount available to be drawn
                  thereunder; and

                        (D) if thirty (30) or fewer days remain prior to
                  the stated expiry date of such Qualified Letter of Credit,the
                  issuer thereof has given the notice of non-extension referred
                  to in clause (D) of paragraph (iii) above, and the Servicer on
                  behalf of the Indenture Trustee (as assignee of the Lessor's
                  rights under the Lease) has not received a Qualified Letter
                  of Credit or an Additional Guaranty to replace such
                  Qualified Letter of Credit, to draw upon such Qualified Letter
                  of Credit in an amount equal to the maximum remaining amount
                  available to be drawn thereunder.

                        The proceeds from each drawing under the Qualified
                 Letter of Credit shall be deposited in the Rent Collection
                 Account and applied pursuant to the provision of the Indenture
                 that would have applied in the


                                       12
<PAGE>

                 event that the payment had been made by the Lessee itself under
                 the circumstances under the Lease giving rise to such payment;
                 provided, however, that the proceeds from any drawing under
                 clause (D) above shall, within five (5) Business Days following
                 the Servicer's receipt of the proceeds of such drawing, be
                 applied (to the extent of such proceeds) by the Indenture
                 Trustee to the purchase of United States Treasury securities
                 identified to the Indenture Trustee by the Guarantor, that are
                 non-callable, that mature as close as possible prior to each
                 succeeding Rent Payment Date and that are in the respective
                 amounts of Base Rent payable on such dates. Upon the
                 receipt by the Servicer on behalf of the Indenture Trustee (as
                 assignee of the Lessor's rights under the Lease)of the proceeds
                 from a drawing under the Qualified Letter of Credit pursuant
                 clause (A), (B) or (C) above, the obligation of the Lessee or
                 the Guarantor to make the corresponding payment under the
                 Lease shall be deemed satisfied, but only to the extent of the
                 amount of such proceeds and without (a)curing any Lease Default
                 or Lease Event of Default relating to such corresponding
                 payment under the Lease except as provided in the final
                 sentence of this paragraph or (b) affecting the obligation of
                 the Lessee or the Guarantor to make any other payment of
                 Base Rent, Supplemental Rent, Stipulated Loss Value
                 Payment, Termination Value Payment or any other
                 amount at any time payable under the Lease or the
                 Guaranty, as the case may be. Upon the purchase by
                 the Indenture Trustee of the United States Treasury
                 securities referred to in the first sentence of this
                 paragraph, the execution of a supplement to the
                 Indenture to accomplish the defeasance of certain
                 obligations of the Lessee that is to be effected by
                 such purchase, the delivery (x) by the Lessee of a
                 tax opinion relating to the defeasance and (y) by the
                 Issuer of a security agreement and a legal opinion
                 relating to such securities and the defeasance
                 effected by the purchase thereof (which supplement to
                 the Indenture, security agreement and legal opinions
                 must be satisfactory in form, scope and substance to
                 the Indenture Trustee and the Majority in Interest of
                 Certificateholders, acting through the Pass-Through
                 Trustee(as such terms are defined in the Indenture)),
                 the Guarantor will no longer be obligated to provide
                 an Additional Guaranty or a Qualified Letter of
                 Credit at such times as it does not maintain
                 Acceptable Debt Ratings (and no Lease Default or
                 Lease Event of Default thereafter shall result solely
                 from its failure to maintain Acceptable Debt Ratings)
                 and the Lessee will be released from its obligation
                 to pay Base Rent during the Base Term (to the extent
                 of the principal amount of such securities at the
                 respective maturities thereof), but without affecting
                 the obligation of the Lessee or the Guarantor to make
                 any other payment of Base Rent or any payment of
                 Supplemental Rent, Stipulated Loss Value Payment,
                 Termination Value Payment or any other amount at any
                 time payable under the Lease or the Guaranty, as the
                 case may be, except to the extent of the net proceeds
                 actually realized by the Indenture Trustee at the
                 respective maturities of such securities or upon the
                 sale or other disposition of such securities pursuant

                                       13
<PAGE>

                 to such security agreement and the other Debt
                 Documents under the circumstances provided therein
                 for such sale or other disposition. To the extent
                 that the proceeds from any drawing under clause (A)
                 or (B) above are received by the Servicer on behalf
                 of the Indenture Trustee (as assignee of the Lessor's
                 rights under the Lease) before the expiration of the
                 applicable grace period under Section 16.1(a) of the
                 Lease, then such receipt shall cure the Lease Default
                 that resulted from the failure of the Lessee to make
                 the payment in question under the Lease.

10. REPRESENTATIONS AND WARRANTIES OF THE GUARANTOR.

The Guarantor represents and warrants as follows:

        (a)  Incorporation, Good Standing and Location.
             ------------------------------------------
         The Guarantor is (i) a corporation duly incorporated, validly existing
         and in good standing under the laws of the State of Texas, (ii) duly
         qualified and authorized to do business and in good standing in every
         other jurisdiction where the nature of its business requires such
         qualification and (iii) has all requisite corporate power and
         authority, and all governmental licenses and permits, to own and
         operate its properties and to carry on its businesses as presently
         conducted. The Guarantor has the requisite corporate power to enter
         into and perform its obligations under this Guaranty Agreement.

         (b) Authorization and Enforceability of Guaranty Agreement.
             ------------------------------------------------------
         The execution, delivery and performance of this Guaranty Agreement have
         been duly authorized by all necessary corporate action on the part of
         the Guarantor. The Guaranty Agreement has been duly and validly
         executed and delivered and constitutes the legal, valid and binding
         obligation of the Guarantor, enforceable against it in accordance with
         its terms, subject to (i) applicable bankruptcy, insolvency,
         moratorium, reorganization, receivership and similar laws affecting the
         rights and remedies of creditors generally, and (ii) general principles
         of equity (regardless of whether such enforceability is considered in a
         proceeding in equity or at law).

         (c) Consents and Approvals:  No Breach,  Adequate  Consideration.
             ------------------------------------------------------------
         All  consents,  approvals,  licenses and  authorizations of, and
         filings and registrations with, any Governmental Authority required
         under Applicable Laws for the execution,  delivery and performance of
         this Guaranty Agreement have been obtained or made and are in full
         force and effect.  The execution,  delivery and performance of this
         Guaranty  Agreement does not and will not violate the provisions of any
         Applicable  Laws, and does not and will not  result in the  breach of,
         or constitute a default or require  any  consent  under, any  material
         agreement, instrument,  or document to which it is a party or by which
         it or any of its property  may be bound or affected.  By virtue of
         its relationship  with Lessee,  the execution, delivery and performance
         of this Guaranty  Agreement is for the direct benefit of Guarantor and
         it has received adequate consideration for this Guaranty Agreement.

11.      NOTICES.  Unless otherwise specifically provided  herein, all notices,
         consents, directions, approvals, instructions, requests and other
         communications required or permitted by the terms hereof shall be in
         writing, and any such communication shall


                                       14
<PAGE>

         become effective when received, addressed in the following manner:
         (a) if to the Guarantor,  to TXU Corp.,  Attention: Treasurer,
         1601 Bryan St., Dallas, Texas 75201, with a copy to Hunton & Williams,
         1601 Bryan Street, Dallas, Texas 75201, or (b) if to Lessor or any
         other  Beneficiary,  to the address of Lessor set forth in the Lease
         and to the address of each other Beneficiary as set forth in the
         Transaction  Documents or as otherwise  provided to  Guarantor by such
         other  Beneficiary; provided,  however,  that any such addressee may
                             --------   -------
         change its address for  communications  by notice given as aforesaid to
         the other parties hereto.

12.      CONSTRUCTION. The section and subsection headings in this Guaranty
         Agreement are for convenience of reference only and shall neither be
         deemed to be a part of this Guaranty Agreement nor modify, define,
         expand or limit any of the terms or provisions hereof. All references
         herein to numbered sections, unless otherwise indicated, are to
         sections of this Guaranty Agreement. Words and definitions in the
         singular shall be read and construed as though in the plural and vice
                                                                          ----
         versa, and words in the masculine, neuter or feminine gender shall be
         -----
         read and construed as though in either of the other genders where the
         context so requires.

13.      SEVERABILITY. If any provision of this Guaranty Agreement, or the
         application thereof to any Person or circumstances, shall, for any
         reason or to any extent, be invalid or unenforceable, such invalidity
         or unenforceability shall not in any manner affect or render invalid or
         unenforceable the remainder of this Guaranty Agreement, and the
         application of that provision to other Persons or circumstances shall
         not be affected but, rather, shall be enforced to the extent permitted
         by applicable law.

14.      SUCCESSORS. The terms and provisions of this Guaranty Agreement shall
         be binding upon the Guarantor and its successors and permitted assigns
         and shall inure to the benefit of the Lessor, the other Beneficiaries
         and their respective successors, transferees and assigns. Without
         limitation of the foregoing sentence, Guarantor hereby consents to the
         assignment by the Lessor to the Indenture Trustee of all of its rights,
         titles, and interests in and to this Guaranty Agreement and the other
         Lease Operative Documents.

15.      ENTIRE AGREEMENT; AMENDMENT. This Guaranty Agreement expresses the
         entire understanding of the subject matter hereof; and all other
         understandings, written or oral, are hereby merged herein and
         superseded. No amendment of or supplement to this Guaranty Agreement,
         or waiver or modification of, or consent under, the terms hereof shall
         be effective unless in writing and signed by the Guarantor, the
         Indenture Trustee, the Lessor, and each Certificateholder; provided,
         however, that the provisions of Section 9 hereof may be amended or
         waived if such amendment or waiver is in writing and signed by the
         Guarantor, the Indenture Trustee, the Lessor, and Certificateholders
         constituting a Majority in Interest of the Certificateholders.

16.      TERM OF GUARANTY AGREEMENT. Subject to Section 6, this Guaranty
         Agreement and all guarantees, covenants and agreements of the Guarantor
         contained herein shall continue in full force and effect and shall not
         be discharged until such time as all of the Guaranteed Obligations
         shall be paid or otherwise discharged in full.



                                       15
<PAGE>

17.      SURVIVAL. All warranties, representations and covenants made by the
         Guarantor herein or in any certificate or other instrument delivered by
         it or on its behalf under this Guaranty Agreement shall be considered
         to have been relied upon by each Beneficiary and shall survive the
         execution and delivery of this Guaranty Agreement, regardless of any
         investigation made by any Beneficiary or on its behalf.

18.      FURTHER ASSURANCES. The Guarantor hereby agrees to execute and deliver
         all such instruments and take all such action as the Lessor may from
         time to time reasonably request in order to effectuate fully the
         purposes of this Guaranty Agreement.

19.      GOVERNING LAW. This Guaranty Agreement has been executed and delivered
         in the State of New York and shall be governed by, construed and
         enforced in all respects in accordance with the laws of the State of
         New York applicable to contracts made and to be performed entirely
         therein, without regard to principles of conflicts of laws.

20.      SUBMISSION TO JURISDICTION.  The Guarantor hereby irrevocably submits
         itself to the nonexclusive  jurisdiction of the Supreme Court of the
         State of New York,  New York County, of the United  States of  America
         and to the  jurisdiction  of the United States District Court for the
         Southern District of New York, for the purpose of any suit, action or
         other proceeding arising out of, or relating to, this Guaranty
         Agreement or the subject  matter hereof, and hereby waives, and agrees
         not to assert, by way of  motion, as a defense or otherwise, in any
         such  suit,  action  or  proceedings,  (i) any  claim  that it is not
         personally  subject to the jurisdiction of the above-named courts for
         any reason  whatsoever,  that such suit,  action or proceeding is
         brought in an inconvenient forum or that the venue of such suit, action
         or proceeding is improper and (ii) any right which it may have to a
         trial by a jury.

                  The Guarantor hereby agrees that the submission to
         jurisdiction referred to in this Section 20 shall not limit in any
         manner the rights of any of the Certificateholders to take proceedings
         against the Guarantor in some other court of competent jurisdiction
         whether within or outside the United States.

21.      REPLACEMENT OF GUARANTOR. If no Lease Default, Lease Event of Default
         or Event of Default shall exist at the time of either such request or
         such release, then following the written request of the Guarantor to
         the Indenture Trustee and the Certificateholders at least thirty (30)
         days prior to the requested date on which the Guarantor is to be
         released from its obligations under this Guaranty Agreement, the
         Guarantor shall be released from further liability under this Guaranty
         Agreement upon its being replaced by a Replacement Guarantor that
         satisfies all the conditions contained in the definition of such term
         set forth in Section 22.

22.      DEFINITIONS. As used herein, the terms listed below shall have the
         definitions specified below. Capitalized terms used but not otherwise
         defined in this Guaranty Agreement shall have the meanings ascribed to
         such terms in the Lease.

                  "Acceptable Debt Ratings" shall mean, with respect to any
         Person, that such Person has a Debt Rating issued by Moody's of at
         least Baa3 or better and a Debt Rating from Standard & Poor's of at
         least BBB-. If any of the foregoing rating categories used by


                                       16
<PAGE>

         Moody's or Standard & Poor's is revised or designated differently (such
         as by changing letter designations to different letter designations or
         to numerical designations), then the references herein to such rating
         shall be changed to the revised or redesignated rating for which the
         standards are closest to, but not lower than, the standards at the date
         hereof for the rating which has been revised or redesignated. If either
         (but not both) of Moody's or Standard & Poor's (including their
         respective successors) shall cease to exist or shall cease to issue
         Debt Ratings generally, then "Acceptable Debt Ratings" shall consist
         solely of the above-required Debt Rating issued by whichever of Moody's
         and Standard & Poor's shall remain in existence or shall continue to
         issue Debt Ratings generally, as the case may be.

                  "Debt Rating" shall mean, with respect to any Person, the
         rating applicable to such Person's senior, unsecured non-credit
         enhanced long-term indebtedness for borrowed money issued by Standard &
         Poor's or Moody's, as applicable. A Debt Rating, whether public or
         private, issued by Standard & Poor's or Moody's shall be deemed to be
         in effect on the date of announcement or publication by Standard &
         Poor's or Moody's, as the case may be, of such Debt Rating or, in the
         absence of such announcement or publication, on the effective date of
         such Debt Rating and will remain in effect until the date when any
         change in such Debt Rating is deemed to be in effect.

                  "Event of Default" shall have the meaning specified in the
         Indenture.

                  "Issuing Bank" shall mean the bank that issues a Qualified
         Letter of Credit.

                  "Majority in Interest of the Certificateholders" shall mean
         the "Majority in Interest of the Holders" as such term is defined in
         the Declaration of Trust.

                  "Material Subsidiary" shall mean any Subsidiary of the
         Guarantor which (i) has contributed more than 5% of the Guarantor's
         consolidated net income (calculated in accordance with GAAP) for the
         fiscal year then most recently ended or (ii) owns assets which
         constitute more than 5% of the Guarantor's consolidated assets
         (calculated in . accordance with GAAP) as of the last day of the fiscal
         year most recently ended.

                  "Ratings Decline" shall mean the existence or occurrence of
         any of the following events: (i) the Guarantor shall cease to have
         Acceptable Debt Ratings; or (ii) either Moody's or Standard & Poor's ,
         or both, shall not have in effect a Debt Rating with respect to the
         Guarantor for any reason whatsoever except the failure of either, but
         not both, of Moody's and Standard & Poor's (including their successors)
         to continue in existence or to issue Debt Ratings generally, as the
         case may be.

                  "Replacement Guarantor" shall mean a Person that satisfies the
         requirements set forth in clauses (i), (ii) (which requirement shall be
         satisfied by the execution and delivery by such Person of a guaranty
         agreement that is in form identical to this Guaranty Agreement, with
         appropriate references revised to reflect the identity and form of
         business organization of such Person), (iv), (v)(A), (vi) and (vii) of
         Section 9(b) of this Guaranty Agreement, recognizing that such Person
         is to replace the Guarantor hereunder

                                       17
<PAGE>

         as the result of a transaction that is not subject to such Section but
         is instead subject to Section 21.

                  "Secured Notes" shall have the meaning given to such term in
         the Indenture.

                  "Solvent" shall mean, when used with respect to any Person,
         means that, as of any date of determination, (a) the amount of the
         "fair value" or "present fair saleable value" of the assets of such
         Person (on a going-concern basis) will, as of such date, exceed the
         amount of all "liabilities of such Person, contingent or otherwise," as
         of such date, as such quoted terms are determined in accordance with
         applicable federal and state laws governing determinations of the
         insolvency of debtors, (b) such fair value or present fair saleable
         value of the assets of such Person (on a going-concern basis) will, as
         of such date, be greater than the amount that will be required to pay
         the liability of such Person on its debts as such debts become absolute
         and matured, (c) such Person will not have, as of such date, an
         unreasonably small amount of capital with which to conduct its
         business, and (d) such Person will be able to pay its debts as they
         mature. For purposes of this definition, (i) "debt" means liability on
         a "claim," (ii) "claim" means any (x) right to payment, whether or not
         such a right is reduced to judgment, liquidated, unliquidated, fixed,
         contingent, matured, unmatured, disputed, undisputed, legal, equitable,
         secured or unsecured or (y) right to an equitable remedy for breach of
         performance if such breach gives rise to a right to payment, whether or
         not such right to an equitable remedy is reduced to judgment, fixed,
         contingent, matured or unmatured, disputed, undisputed, secured or
         unsecured and (iii) unliquidated, contingent, disputed and unmatured
         claims shall be valued at the amount that can be reasonably expected to
         be actual and matured.

                  "Subsidiary" shall mean (i) any corporation, at least 50% of
         the total combined voting power of all classes of Voting Stock of which
         shall, at the time as of which any determination is being made, be
         owned by the Guarantor, either directly or through Subsidiaries, and
         (ii) any partnership, joint venture or similar entity if at least a 50%
         interest in the profits or capital thereof is owned by the Guarantor,
         either directly or through Subsidiaries (unless such entity can and
         does ordinarily take major business actions without the prior approval,
         direct or indirect, of the Guarantor).

                  "Surviving Entity" shall have the meaning specified in Section
         9(b)(i) of this Guaranty Agreement.

                  "Trust Certificates" shall mean the "Certificates" as such
         term is defined in the Declaration of Trust.

                  "Voting Stock" shall mean, with respect to any corporation,
         any shares of stock of such corporation whose holders are entitled
         under ordinary circumstances to vote for the election of directors of
         such corporation (irrespective of whether at the time stock of any
         other class or classes shall have or might have voting power by reason
         of the happening of any contingency).

         [Remainder of page is intentionally left blank; signature page follows]

                                       18
<PAGE>

         IN WITNESS WHEREOF, the Guarantor has caused this Guaranty Agreement to
be duly executed and delivered as of the date and year first above written.

                                    TXU CORP.


                                    By:      /s/Kirk R. Oliver
                                       ----------------------------------------
                                             Kirk R. Oliver, Treasurer