Exhibit
      10.1


**FIRST
        AMENDMENT TO LEASE AGREEMENT**
  This
        First Amendment to Lease Agreement (this “Amendment”) is dated as of June 1,
        2007, by and between U.S. Bank, N.A. (as successor-in-interest to State Street
        Bank and Trust Company of Connecticut, National Association), as owner trustee
        of ZSF/Dallas Tower Trust, a Delaware grantor trust (as trustee only, and
        not
        individually) (“Lessor”), and TXU Properties Company, a Texas corporation
        (“Lessee”).
  **W
        I T N E S S E T H :**
  WHEREAS,
        by that certain Lease Agreement, dated as of February 14, 2002 (the “Lease”)
        between Lessor and Lessee, Lessor demised and leased to Lessee and Lessee
        rented
        and leased from Lessor the Property (as defined in the Lease); and
  WHEREAS,
        Lessor and Lessee desire to make certain modifications to the Lease subject
        to
        the terms hereof.
  NOW,
        THEREFORE, in consideration of the sum of Ten Dollars ($10.00) and other
        good
        and valuable consideration, the receipt and sufficiency of which are hereby
        mutually acknowledged, Lessor and Lessee hereby agree as follows:
  1.           Defined
        Terms.  Capitalized terms used but not defined in this Amendment
        shall have the same meanings as are ascribed to them in the Lease, unless
        otherwise noted.
 
 2.           Modifications
        to Lease.  The Lease is hereby amended, modified and supplemented
        as follows:
 
 (a)           Section
        7.1 is hereby modified by deleting the words “Guarantor (or Lessee if there
        is no Guarantor)” appearing in line 10 thereof and substituting in lieu thereof
        the word “Lessee”.
 
 (b)           Section
        8.5(a) is hereby modified by: (i) deleting the words “(or Guarantor)”
appearing in lines 16-17 thereof; and (ii) deleting the words “Guarantor (or
        Lessee if there is no Guarantor)” appearing in line 31 thereof and substituting
        in lieu thereof the word “Lessee”.
 
 (c)           Section
        8.6 is hereby modified by deleting the words “(or Guarantor)” appearing in
        line 26 thereof.
 
 (d)           Section
        9.1(b) is hereby modified by deleting the words “Guarantor (or Lessee if
        there is no Guarantor)” appearing in line 2 thereof and substituting in lieu
        thereof the word “Lessee”.
 
 (e)           Section
        11.1 is hereby modified by deleting the terms of the section in their
        entirety and substituting in lieu thereof the following:
  1
  “*Assignment
        by Lessee*.  So long as no Lease Event of Default has occurred and
        is continuing, Lessee may, at Lessee’s sole expense, without the consent of
        Lessor, assign this Lease for a period that does not extend beyond the Lease
        Term, to any Affiliate of Lessee that is not, and will at no time be, an
        Obligor, *provided, however*, that any such Affiliate is not (I) a
        tax-exempt entity (within the meaning of Section 168(h) of the Code) or (II)
        a
        debtor or debtor-in-possession in a voluntary or involuntary bankruptcy
        proceeding at the commencement of the assignment.  For purposes
        hereof, an assignment shall be deemed any merger or consolidation of Lessee
        which would violate the provisions of (I) or (II) above.  Any assignee
        shall assume in writing any obligations of Lessee arising from and after
        the
        effective date of the assignment, *provided, however*, that no such
        assignment shall become effective until (i) a fully executed copy of an
        assignment and assumption agreement, reasonably acceptable to Lessor, Servicer,
        Indenture Trustee and Lessee, shall have been delivered to Lessor, the Servicer
        and the Indenture Trustee, and (ii) such assignee shall have executed such
        instruments and other documents and provided such further assurances as the
        Indenture Trustee shall reasonably request to ensure that such assignment
        is
        subject to the Assignment of Lease, the other Debt Documents and this Lease
        and
        is enforceable.  Notwithstanding any such assignment, Lessee shall not
        be released from its primary liability hereunder and shall continue to be
        obligated for all of its obligations in this Lease, which obligations shall
        continue in full effect as obligations of a principal and not of a guarantor
        or
        surety, as though no assignment had been made.  Lessee will have the
        right, subsequent to any assignment (a) to receive a duplicate copy of each
        notice of default sent by Lessor to Lessee or any assignee (but such notice
        shall be effective as against the Lessee, as well as any subsequent assignees,
        even if a copy has not been delivered to such requesting assignee), and (b)
        to
        cure any default by Lessee or other assignee under the Lease within the cure
        period provided for hereunder.  Lessee’s liability hereunder shall
        continue notwithstanding the rejection of this Lease by an assignee or any
        sublease of this Lease pursuant to Section 365 of Title 11 of the United
        States
        Code, any other provision of the Bankruptcy Code, or any similar law relating
        to
        bankruptcy, insolvency, reorganization or the rights of creditors, which
        arises
        subsequent to such assignment.  In the event Lessee assigns this Lease
        and it shall thereafter be rejected in a bankruptcy or similar proceeding,
        a new
        lease identical to this Lease shall be reinstituted as between Lessor and
        Lessee
        without further act of either party, provided Lessor shall not be obligated
        to
        deliver to Lessee possession of the Property free of any tenancy created
        or
        caused by Lessee or any entity holding by or through Lessee.  Nothing
        herein shall be construed to permit Lessee to mortgage, pledge, hypothecate
        or
        otherwise collaterally assign in any manner or nature whatsoever Lessee’s
        interest under this Lease in whole or in part. Lessee shall provide written
        notice to Lessor, the Servicer and the Indenture Trustee of any proposed
        assignment of this Lease at least thirty (30) Business Days prior to the
        effective date thereof and an executed copy of the approved agreement of
        assignment and assumption within thirty (30) days after the execution
        thereof.  To the extent an assignee of this Lease fails to perform on
        behalf of Lessee the obligations of Lessee hereunder, and Lessee performs
        such
        obligations, then Lessee shall be subrogated to the rights of Lessor as against
        such assignee in respect of such performance.”
  2
  
 (f)           Section12.1 is hereby modified by deleting the word “Guarantor” appearing in line
        67 thereof and substituting in lieu thereof the word “Lessee”.
 
 (g)           Article
        13 is hereby restated in its entirety as follows:
 
 “ARTICLE
        13
 LETTER
        OF CREDIT
 
 Section
        13.1.  *Letter of Credit*.  Throughout the Base Term
        and all applicable Renewal Terms, the Lessee shall cause the Applicant to
        provide a Qualified Letter of Credit satisfying the requirements set forth
        in
        this Article 13; provided that in the event of a draw pursuant to Section
        13.3(b), (c), (d), (e), (f) or (g) below, the Lessee shall no longer have
        an
        obligation to cause the Applicant to provide a Qualified Letter of
        Credit.  In addition, the Lessee shall cause each Obligor to waive all
        direct or indirect rights of reimbursement, subrogation or other claims against
        the Lessee with respect to such Qualified Letter of Credit.
 
 Section
        13.2.  *Replacements*.  The Applicant shall have the
        right at any time to replace any outstanding Qualified Letter of Credit with
        another Qualified Letter of Credit that meets all of the requirements set
        forth
        in this Article 13.  Each replacement Qualified Letter of Credit shall
        be accompanied by a certificate executed by Lessee confirming (a) each
        Obligor has waived all direct or indirect rights of reimbursement, subrogation
        or other claims against the Lessee with respect to such replacement Qualified
        Letter of Credit, (b) Lessee is not an Obligor with respect to such
        replacement Qualified Letter of Credit, and (c) such replacement Qualified
        Letter of Credit is not collateralized with any asset in which the Lessee
        has an
        ownership or other interest.
 
 Section
        13.3.*Draw
        Events*.With
        respect to any Qualified Letter of Credit, the
        Beneficiary****shall be permitted thereunder:
 
 (a) from
        time to
        time, if the Lessee fails to make any payment of Base Rent on an applicable
        Rent
        Payment Date, to draw upon such Qualified Letter of Credit an amount equal
        to or
        less than the amount of Base Rent that on such Rent Payment Date was due
        and
        payable but not paid and that remains unpaid on the date of such
        drawing;****
 
 (b) if
        Lessee
        fails to make a Stipulated Loss Value Payment due and payable on a Stipulated
        Loss Value Date pursuant to Section 12.1, to draw upon such Qualified Letter
        of
        Credit an amount equal to or less than the Stipulated Loss Value Payment
        that on
        such Stipulated Loss Value Date was due and payable but not paid and that
        remains unpaid on the date of such drawing;
 
 (c) if
        any Lease
        Event of Default has occurred and is continuing, to draw upon such Qualified
        Letter of Credit an amount equal to the maximum remaining amount available
        to be
        drawn thereunder;
  3
  (d)if(i)
        an Obligor
        makes any general arrangement or assignment for the benefit of creditors;
        (ii)
        an Obligor becomes a “debtor” as defined in 11 U.S.C. § 101 of the
        Bankruptcy Code or any successor statute thereto (unless, in the case of
        a
        petition filed against such Obligor, the same is dismissed within ninety
        (90)
        days or such Obligor ceases to be an “Obligor” within ninety (90) days); (iii)
        the appointment of a trustee or receiver to take possession of substantially
        all
        of the assets of an Obligor where possession is not restored to such Obligor
        within ninety (90) days and such Obligor does not cease to be an “Obligor”
within ninety (90) days; (iv) the attachment, execution or other judicial
        seizure of substantially all of the assets of an Obligor where such attachment,
        execution or other judicial seizure is not discharged within ninety (90)
        days
        and such Obligor does not cease to be an “Obligor” within ninety (90) days; (v)
        an Obligor admits in writing its inability to pay its debts generally as
        they
        become due; (vi) an Obligor files a petition in bankruptcy or a petition to
        take advantage of any insolvency act; (vii) an Obligor files a petition or
        answer seeking reorganization or arrangement or other protection under the
        Federal bankruptcy laws or any other applicable law or statute of the United
        States of America or any State thereof; (viii) an Obligor is liquidated or
        dissolved, or placed under conservatorship or other protection under any
        applicable federal or state law or begins proceedings toward such liquidation
        or
        dissolution; (ix) any petition is filed by or against an Obligor under Federal
        bankruptcy laws, or any other proceeding is instituted by or against an Obligor
        seeking to adjudicate it a bankrupt or insolvent, or seeking liquidation,
        reorganization, arrangement, adjustment or composition of it or its debts
        under
        any law relating to bankruptcy, insolvency or reorganization or relief of
        debtors, or seeking the entry of an order for relief or the appointment of
        a
        receiver, trustee, custodian or other similar official for an Obligor, or
        for
        any substantial part of the property of an Obligor, and such proceeding is
        not
        dismissed within ninety (90) days after institution thereof and such Obligor
        does not cease to be an “Obligor” within ninety (90) days after institution
        thereof; or (x) an Obligor shall take any action to authorize or effect any
        of
        the actions set forth above in this subsection (d), to draw to draw upon
        such
        Qualified Letter of Credit an amount equal to the maximum remaining amount
        available to be drawn thereunder;
 
 (e)if(i) an
        Obligor has any rights of reimbursement, subrogation or other claims against
        the
        Lessee with respect to such Qualified Letter of Credit, (ii) Lessee is an
        Obligor with respect to such Qualified Letter of Credit, or (iii) such
        Qualified Letter of Credit is collateralized with any asset in which the
        Lessee
        has an ownership or other interest, to draw upon
        such
        Qualified Letter of Credit an amount equal to the maximum remaining amount
        available to be drawn thereunder;
 
 (f) if
        thirty
        (30) or fewer days remain prior to the current expiry date of such Qualified
        Letter of Credit, the Issuing Bank has given a notice of non-extension referred
        to in the definition of “Qualified Letter of Credit”, and the Beneficiaryhas
        not received a replacement Qualified Letter of Credit under
  4
  Section
        13.2, to draw upon such Qualified Letter of Credit an amount equal to the
        maximum remaining amount available to be drawn thereunder; and
 
 (g)ifthe
        Lessee fails
        to cause the Applicant to provide a required Qualifying Letter of Credit
        (as
        defined in the Master Letter Agreement) by May
 15,
        2022 in accordance with Section 5(a) of the Master Letter Agreement, and the
        Beneficiaryhas not
        received a
        Qualifying Letter of Credit,to draw upon
        such Qualified Letter
        of Creditan amount equal to or less than the amount of the Qualifying
        Letter of Credit that was required to be provided pursuant to Section 5(a)
        of
        the Master Letter Agreement;
 
 provided
        that an authorized representative or officer of the Beneficiary delivers
        to the
        Issuing Bank a certificate as to the occurrence of the condition allowing
        such
        draw.
 
 Section
        13.4.  *Letter of Credit Proceeds*.  Upon a draw on a
        Qualified Letter of Credit by the Beneficiary, the proceeds shall be deposited
        and handled as set forth in that certain Master Letter Agreement dated as
        of
        even date herewith (the “**Master Letter
        Agreement**”).
 
 Section
        13.5.  *Lessor Payment Obligation*.  Notwithstanding
        any provision in the Master Letter Agreement to the contrary, the Lessor
        shall
        be obligated to pay to the Applicant within ninety (90) days after the
        termination of this Lease an amount equal to the portion of the LOC Account
        Excess Amount (as defined in the Master Letter Agreement) received by the
        Lessor, if any, that is not required to be used to satisfy the Lessee’s unpaid
        obligations under this Lease.  In no event shall the amount of such
        payment exceed an amount equal to the LOC Account Excess Amount actually
        received by the Lessor.  The Lessor hereby covenants and agrees that
        it will continue to comply with its covenants and agreements set forth in
        Section 5.01 and Section 5.02 of the Indenture, as in effect on the date
        hereof,
        until such time as any amount due and payable to the Applicant under this
        Section 13.5 or under Section 4(b)(vi)(B) of the Master Letter Agreement
        is paid
        to the Applicant.
 
 Section
        13.6.  *Quarterly Compliance Certificate*.  Within
        thirty (30) days after the end of each calendar quarter in each calendar
        year
        during the Base Term and all applicable Renewal Terms, the Lessee shall deliver
        to the Lessor, the Indenture Trustee and the Beneficiary a certificate executed
        by Lessee confirming (a) each Obligor has waived all direct or indirect
        rights of reimbursement, subrogation or other claims against the Lessee with
        respect to any outstanding Qualified Letter of Credit, (b) Lessee is not an
        Obligor with respect to any such Qualified Letter of Credit, and (c) such
        Qualified Letter of Credit is not collateralized with any asset in which
        the
        Lessee has an ownership or other interest.”
 
 (h)           Section
        15.1 is hereby modified by deleting the words “or Guarantor” appearing in
        line 29 thereof.
  5
  (i)           Section
        16.1(a) is hereby modified by deleting the terms of the section in
        their entirety and substituting in lieu thereof the following:
 
 Lessee
        shall fail to make any Termination Value Payment or Stipulated Loss Value
        Payment within three (3) Business Days after the same shall become
        due;
 
 (j)           Section
        16.1(b) is hereby modified by deleting the terms of the section in
        their entirety and substituting in lieu thereof the following:
 
 Lessee
        shall fail to make any payment of Base Rent, Supplemental Rent or any other
        payment required to be made under this Lease and such failure shall continue
        for
        a period of ten (10) days after written notice thereof from Lessor or the
        Servicer;
 
 (k)           Section
        16.1(c) is hereby modified by: (i) deleting the words “any of Guarantor or”
appearing in line 1 thereof; and (ii) deleting the words “Guarantor or Lessee
        (as applicable)” appearing in line 7 thereof and substituting in lieu thereof
        the word “Lessee”.
 
 (l)           Section
        16.1(e) is hereby modified by: (i) deleting the
        words “the Guarantor or” appearing in line 1 thereof; and (ii) deleting the
        words “Guarantor or” appearing in line 2 thereof.
 
 (m)           Section
        16.1(f) is hereby modified by deleting the words “or Guarantor” appearing in
        lines 1, 2, 4, 5, 6, 7-8 (both occurrences), 9-10, 11, 13, 16, 17, 21, 22
        and 24
        thereof.
 
 (n)           Section
        16.1(g) is hereby modified by deleting the terms of the section in their
        entirety.
 
 (o)           Section
        19.1(a) is hereby modified by: (i) deleting the words “or Guarantor”
appearing in line 32 thereof; and (ii) deleting the words “or the Guaranty, as
        applicable,” appearing in line 33 thereof.
 
 (p)           Appendix
        A is hereby modified by:
 
 i.           adding
        the following definition of “Acceptable Bank”:
 
 “**“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 event that either
        Moody’s or Standard & Poor’s (including their respective successors) shall
        have ceased to exist).”
 
 ii.           restating
        the definition of “Address” as follows:
  6
  “**“****Address****”**shall mean, subject to the rights of the party in question to change
        its Address in accordance with the terms of the Operative
        Documents:
 (i)           with
        respect to Lessee:  TXU Properties Company, 1601 Bryan Street, Dallas,
        Texas 75201, Attention:  Treasurer.
  (ii)           with
        respect to Lessor:  c/o U.S. Bank, N.A. (as successor-in-interest to
        State Street Bank and Trust Company of Connecticut, National Association),
        as
        Owner Trustee, 1 Federal Street, 3rd Floor,
        Boston,
        Massachusetts 02110, Attention: Corporate Trust Administration;
  with
        a copy to the Owner Participant:  ZSF/Dallas Tower LLC, c/o Zurich
        Structured Finance, Inc., 105 East 17th Street,
        New York,
        New York 10005, Attention: Mr. Christian Halabi;
  with
        an additional copy to the Owner Participant:  ZSF/Dallas Tower LLC,
        c/o Zurich Structured Finance, Inc., 105 East 17th Street,
        New York,
        New York 10005,  Attention:  General Counsel;
  with
        an additional copy to Neil Tucker:  Kramer Levin Naftalis &
Frankel LLP, 1177 Avenue of the Americas, 27th Floor,
        New York,
        New York 10036, Attention:  Mr. Neil Tucker.
  (iii)           with
        respect to the Indenture Trustee:  LaSalle Bank National Association,
        135 South LaSalle Street, Suite 1625, Chicago, Illinois 60603,
        Attention:  GSTS - TXU Pass-Through Trust, Series 2002-1;
  with
        a copy to the Servicer:  Wachovia Bank, National Association, 301
        South College Street, NC 0606, Charlotte, NC  28288;
  with
        an additional copy to each of the following holders of Pass-Through Trust
        Certificates (so long as such holders continue to own Pass-Through Trust
        Certificates):  (a) The Prudential Insurance Company of America,
        c/o Prudential Capital Group, 2200 Ross Avenue, Suite 4200E, Dallas,
        TX  75201; (b) Allstate Life Insurance Company, Private
        Placements Department, 3075 Sanders Road, STE G5D, Northbrook, Illinois
        60062-7127; (c) Allstate Life Insurance Company of New York, Private
        Placements Department, 3075 Sanders Road, STE G5D, Northbrook, Illinois
        60062-7127; (d) Nationwide Life Insurance Company, One Nationwide Plaza
        (1-33-07), Columbus, Ohio  43215-2220; (e) Nationwide Life and
        Annuity Insurance Company, One Nationwide Plaza (1-33-07), Columbus,
        Ohio  43215-2220; (f) Thrivent Financial for Lutherans, Attn: Al
        Onstad, 625 Fourth Avenue South, Minneapolis,
        Minnesota  55415.
  (iv)           with
        respect to the Servicer:  Wachovia Bank, National Association, 301
        South College Street, NC 0606, Charlotte, NC  28288;
  7
  with
        a copy to the Indenture Trustee:  LaSalle Bank National Association,
        135 South LaSalle Street, Suite 1625, Chicago, Illinois 60603,
        Attention:  GSTS - TXU Pass-Through Trust, Series 2002-1;
 
 iii.           adding
        the following definition of “Applicant”:
 
 “**“****Applicant****”**shall mean TXU Corp. or any Affiliate of TXU Corp. other than the
        Lessee.”
 
 iv.           adding
        the following definition of “Beneficiary”:
 
 “**“****Beneficiary****”**shall mean the Servicer, acting on behalf of the Indenture Trustee,
        as
        assignee of the Lessor’s rights under the Lease, and its successors and assigns,
        including any permitted assignees of its rights and obligations with respect
        to
        any Qualified Letter of Credit.”
 
 v.           adding
        the following definition of “Debt Rating”:
 
 “**“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.”
 
 vi.           deleting
        the definition of “Guarantor.”
 
 vii.           deleting
        the definition of “Guaranty.”
 
 viii.           adding
        the following definition of “Issuing Bank”:
 
 “**“Issuing
        Bank”** shall mean an Acceptable Bank that issues a Qualified Letter of
        Credit.”
 
 ix.           restating
        the following definition of “Lease”:
 
 “**“Lease”**
        shall mean the Lease Agreement dated as of the Closing Date between Lessor,
        as
        lessor, and Lessee, as lessee, as amended by that certain First Amendment
        to
        Lease Agreement dated as of June 1, 2007.”
 
 x.           within
        the definition of “Lease Operative Documents”, deleting reference therein to
“the Guaranty”;
  8
  xi.           adding
        the following definition of “Majority in Interest of the
        Certificateholders”:
 
 “**“Majority
        in Interest of the Certificateholders**”****shall mean
        the “Majority in Interest of the Holders” as such term is defined in the
        Pass-Through Trust Agreement.”
 
 xii.           adding
        the following definition of “Master Latter Agreement”:
 
 “**“Master
        Letter Agreement**”****shall have the meaning
        specified in Section 13.4 of the Lease.”
 
 xiii.           within
        the definition of “Net Casualty Proceeds”, deleting the words “, the Guarantor”
appearing in line 4 thereof;
 
 xiv.           within
        the definition of “Net Condemnation Proceeds”, deleting the words “, the
        Guarantor” appearing in line 3 thereof;
 
 xv.           adding
        the following definition of “Obligor”:
 
 “**“Obligor”**
        shall mean, with respect to any Qualified Letter of Credit that is outstanding,
        each entity that is directly or indirectly obligated to reimburse the Issuing
        Bank for any amounts drawn under such Qualified Letter of Credit; *provided,
        however*, that the term “Obligor” shall not include any entity which, on the
        day on which Beneficiary would otherwise be entitled to draw on such Qualified
        Letter of Credit, is not directly or indirectly obligated to reimburse the
        Issuing Bank for any amounts drawn under such Qualified Letter of
        Credit.”
 
 xvi.           within
        sub-item (c) of the definition of “Permitted Liens”, deleting the word
“Guarantor” appearing in line 7 thereof and substituting in lieu thereof the
        word “Lessee”;
 
 xvii.           within
        sub-item (d) of the definition of “Permitted Liens”, (1) deleting the words
“Guarantor (or Lessee if there is no Guarantor)” appearing in lines 4-5 thereof
        and substituting in lieu thereof the word “Lessee”, and (2) deleting the word
“Guarantor” appearing in line 7 thereof and substituting in lieu thereof the
        word “Lessee”;
 
 xviii.          within
        the final paragraph of the definition of “Permitted Liens”, deleting the words
“Guarantor’s and” appearing in line 4 thereof;
 
 xix.           adding
        the following definition of “Qualified Letter of Credit”:
 
 “**“Qualified
        Letter of Credit”** shall mean an irrevocable, standby letter of
        credit issued, at the request of Applicant, by an Acceptable Bank in favor
        of
        the
  9
  Beneficiary,
        substantially in form of Exhibit D attached to the Master Letter Agreement,
        or
        otherwise in form and substance reasonably satisfactory to the Lessor and
        the
        Majority in Interest of the Certificateholders and satisfying all of the
        following criteria:
 
 (A)           at no time
        shall the Lessee be an Obligor with respect to such letter of
        credit;
 
 (B)           such
        letter of credit shall at no time be collateralized with any asset in which
        the
        Lessee has an ownership or other interest;
 
 (C)           such
        letter of credit shall at all times be at least equal to (1) $5,000,000,
        plus (2) the greater of (I) the aggregate Base Rent then remaining to be
        paid over the remainder of the scheduled Base Term and (II) the largest
        Stipulated Loss Value listed on Schedule 12.1 to the Lease that may become
        payable by the Lessee during the remainder of the scheduled Base Term,
provided that in the event of a partial draw pursuant to clause (E)(I)
        below that reduces the amount of such letter of credit below the required
        minimum amount described above, Applicant shall have thirty (30) days to
        increase or replace such letter of credit so that the amount of such letter
        of
        credit or the replacement letter of credit is equal to or greater than the
        required minimum amount described above;
 
 (D)           (I) with
        respect to the Base Term, such letter of credit shall have a stated expiry
        date
        which is the sooner to occur of (a) May 31, 2022 or (b) a date that is at
        least one year from date of the issuance thereof, and, if such expiry date
        is
        prior to May 31, 2022, 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 (but in no event beyond May 31, 2022) *unless* the
        Issuing Bank shall, not later than 60 days prior to the stated expiry date,
        provide written notice to the Applicant, the Servicer, acting on behalf of
        the
        Indenture Trustee (as assignee of the Lessor’s rights under the Lease), and the
        Lessor, stating that the Issuing Bank elects not to automatically extend
        such
        letter of credit for any additional period; or (II) with respect to any
        Renewal Term, such letter of credit shall have a stated expiry date which
        is the
        sooner to occur of (a) ninety (90) days after the expiration of such Renewal
        Term or (b) a date that is at least one year from date of the issuance
        thereof, and, if such expiry date is prior to the date that is ninety (90)
        days
        after the expiration of such Renewal 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 (but in no event beyond the date that is
        ninety
        (90) days after the expiration of such Renewal Term) *unless* the Issuing
        Bank shall, not later than 60 days prior to the stated expiry date, provide
        written notice to the Applicant and the Lessor, stating that the Issuing
        Bank
        elects not to automatically extend such letter of credit for any additional
        period;
 
 (E)           such
        letter of credit shall provide that it may be drawn in whole or in part,
        with
        funds under such letter of credit being available to the
        Beneficiary
  10
  against
        presentation at the Issuing Bank’s office, in person, via courier or other
        delivery service, on or before the expiry date of such letter of credit,
        of the
        Beneficiary’s sight draft(s) drawn on the Issuing Bank and accompanied by a
        written statement signed by an authorized representative or officer of the
        Beneficiary reading as one of the following (with the blanks filled
        in):
 
 (I)           “WE
        HEREBY CERTIFY THAT THE LESSEE FAILED TO MAKE PAYMENT OF BASE RENT DUE AND
        PAYABLE ON _________ PURSUANT TO THAT CERTAIN LEASE AGREEMENT DATED AS OF
        FEBRUARY 14, 2002, AS AMENDED, FOR THE PROPERTY CURRENTLY OR PREVIOUSLY KNOWN
        AS
        ENERGY PLAZA IN DALLAS, TEXAS, AND THE AMOUNT OF THIS DRAWING, $______________,
        AN AMOUNT EQUAL TO OR LESS THAN THE AMOUNT OF BASE RENT THAT ON SUCH DATE
        WAS
        DUE AND PAYABLE PURSUANT TO THE LEASE BUT NOT PAID, REMAINS UNPAID AS OF
        THE
        DATE HEREOF.”
 
 OR
 
 (II)           "WE
        HEREBY CERTIFY THAT THE LESSEE FAILED TO MAKE A STIPULATED LOSS VALUE PAYMENT
        DUE AND PAYABLE ON _________ PURSUANT TO THAT CERTAIN LEASE AGREEMENT DATED
        AS
        OF FEBRUARY 14, 2002, AS AMENDED, FOR THE PROPERTY CURRENTLY OR PREVIOUSLY
        KNOWN
        AS ENERGY PLAZA IN DALLAS, TEXAS, AND THE AMOUNT OF THIS DRAWING, $__________,
        AN AMOUNT EQUAL TO OR LESS THAN THE STIPULATED LOSS VALUE PAYMENT THAT ON
        SUCH
        DATE WAS DUE AND PAYABLE PURSUANT TO THE LEASE BUT NOT PAID, REMAINS UNPAID
        AS
        OF THE DATE HEREOF."
 
 OR
 
 (III)           "WE
        HEREBY CERTIFY THAT A LEASE EVENT OF DEFAULT HAS OCCURRED AND IS CONTINUING
        PURSUANT TO THAT CERTAIN LEASE AGREEMENT DATED AS OF FEBRUARY 14, 2002, AS
        AMENDED, FOR THE PROPERTY CURRENTLY OR PREVIOUSLY KNOWN AS ENERGY PLAZA IN
        DALLAS, TEXAS, AND THE BENEFICIARY HEREBY DRAWS $___________, THE MAXIMUM
        REMAINING AMOUNT AVAILABLE TO BE DRAWN UNDER THE LETTER OF CREDIT."
 
 OR
 
 (IV)           "WE
        HEREBY CERTIFY THAT (A) AN “OBLIGOR” (AS DEFINED IN THAT CERTAIN LEASE AGREEMENT
        DATED AS OF FEBRUARY 14, 2002, AS AMENDED, FOR THE PROPERTY CURRENTLY OR
        PREVIOUSLY KNOWN AS ENERGY PLAZA IN DALLAS, TEXAS) HAS MADE A GENERAL
        ARRANGEMENT OR ASSIGNMENT FOR THE BENEFIT OF CREDITORS; (B) AN OBLIGOR HAS
        BECOME A “DEBTOR” AS DEFINED IN 11 U.S.C. § 101 OF THE BANKRUPTCY CODE OR
        ANY SUCCESSOR STATUTE THERETO (AND, IN THE CASE OF A PETITION FILED AGAINST
        SUCH
        OBLIGOR, THE PETITION WAS FILED AT LEAST NINETY (90) DAYS PRIOR TO THE DATE
        OF
        THIS DRAWING AND HAS NOT BEEN DISMISSED); (C) AT LEAST NINETY (90) DAYS PRIOR
        TO
        THE DATE OF THIS DRAWING THERE WAS AN APPOINTMENT OF A TRUSTEE OR RECEIVER
        TO
        TAKE POSSESSION OF SUBSTANTIALLY ALL OF THE ASSETS OF AN OBLIGOR AND POSSESSION
        HAS NOT BEEN RESTORED; (D) THERE OCCURRED AN ATTACHMENT, EXECUTION OR OTHER
        JUDICIAL SEIZURE OF SUBSTANTIALLY ALL OF THE ASSETS OF AN OBLIGOR
        AT
  11
  LEAST
        NINETY (90) DAYS PRIOR TO THE DATE OF THIS DRAWING AND SUCH ATTACHMENT,
        EXECUTION OR OTHER JUDICIAL SEIZURE HAS NOT BEEN DISCHARGED; (E) AN OBLIGOR
        HAS
        ADMITTED IN WRITING ITS INABILITY TO PAY ITS DEBTS GENERALLY AS THEY BECOME
        DUE;
        (F) AN OBLIGOR HAS FILED A PETITION IN BANKRUPTCY OR A PETITION TO TAKE
        ADVANTAGE OF ANY INSOLVENCY ACT; (G) AN OBLIGOR HAS FILED A PETITION
        OR ANSWER SEEKING REORGANIZATION OR ARRANGEMENT OR OTHER PROTECTION UNDER
        THE
        FEDERAL BANKRUPTCY LAWS OR ANY OTHER APPLICABLE LAW OR STATUTE OF THE UNITED
        STATES OF AMERICA OR ANY STATE THEREOF; (H) AN OBLIGOR HAS LIQUIDATED OR
        DISSOLVED, OR BEEN PLACED UNDER CONSERVATORSHIP OR OTHER PROTECTION UNDER
        ANY
        APPLICABLE FEDERAL OR STATE LAW OR BEGAN PROCEEDINGS TOWARD SUCH LIQUIDATION
        OR
        DISSOLUTION; (I) A PETITION HAS BEEN FILED AT LEAST NINETY (90) DAYS PRIOR
        TO
        THE DATE OF THIS DRAWING BY OR AGAINST AN OBLIGOR UNDER FEDERAL BANKRUPTCY
        LAWS,
        OR ANOTHER PROCEEDING HAS BEEN INSTITUTED AT LEAST NINETY (90) DAYS PRIOR
        TO THE
        DATE OF THIS DRAWING BY OR AGAINST AN OBLIGOR SEEKING TO ADJUDICATE IT BANKRUPT
        OR INSOLVENT, OR SEEKING LIQUIDATION, REORGANIZATION, ARRANGEMENT, ADJUSTMENT
        OR
        COMPOSITION OF IT OR ITS DEBTS UNDER ANY LAW RELATING TO BANKRUPTCY, INSOLVENCY
        OR REORGANIZATION OR RELIEF OF DEBTORS, OR SEEKING THE ENTRY OF AN ORDER
        FOR
        RELIEF OR THE APPOINTMENT OF A RECEIVER, TRUSTEE, CUSTODIAN OR OTHER SIMILAR
        OFFICIAL FOR SUCH OBLIGOR, OR FOR ANY SUBSTANTIAL PART OF THE PROPERTY OF
        SUCH
        OBLIGOR, AND SUCH PROCEEDING HAS NOT BEEN DISMISSED; OR (J) AN OBLIGOR HAS
        TAKEN
        AN ACTION TO AUTHORIZE OR EFFECT ANY OF THE ACTIONS SET FORTH ABOVE, AND
        THE
        BENEFICIARY HEREBY DRAWS $___________, THE MAXIMUM REMAINING AMOUNT AVAILABLE
        TO
        BE DRAWN UNDER THE LETTER OF CREDIT."
 
 OR
 
 (V)           "WE
        HEREBY CERTIFY THAT (A) AN “OBLIGOR” (AS DEFINED IN THAT CERTAIN LEASE AGREEMENT
        DATED AS OF FEBRUARY 14, 2002, AS AMENDED, FOR THE PROPERTY CURRENTLY OR
        PREVIOUSLY KNOWN AS ENERGY PLAZA IN DALLAS, TEXAS) HAS RIGHTS OF REIMBURSEMENT,
        SUBROGATION OR OTHER CLAIMS WITH RESPECT TO SUCH LETTER OF CREDIT AGAINST
        THE
        LESSEE UNDER SUCH LEASE AGREEMENT, (II) THE LESSEE IS DIRECTLY OR
        INDIRECTLY OBLIGATED TO REIMBURSE BANK FOR ANY AMOUNTS DRAWN UNDER BANK
        IRREVOCABLE STANDYBY LETTER OF CREDIT NO. _________________, OR (III) SUCH
        LETTER OF CREDIT IS COLLATERALIZED WITH ANY ASSET IN WHICH THE LESSEE HAS
        AN
        OWNERSHIP OR OTHER INTEREST, AND THE BENEFICIARY HEREBY DRAWS $___________,
        THE
        MAXIMUM REMAINING AMOUNT AVAILABLE TO BE DRAWN UNDER THE LETTER OF
        CREDIT."
 
 OR
 
 (VI)           "WE
        HEREBY CERTIFY THAT THIRTY (30) OR FEWER DAYS REMAIN PRIOR TO THE CURRENT
        EXPIRY
        DATE OF THIS LETTER OF CREDIT, BANK HAS GIVEN NOTICE OF NON-EXTENSION AND
        THE
        SERVICER ON BEHALF OF THE INDENTURE TRUSTEE HAS NOT RECEIVED A QUALIFIED
        LETTER
        OF CREDIT AND BENEFICIARY IS ENTITLED TO DRAW $___________, THE MAXIMUM
        REMAINING AMOUNT AVAILABLE TO BE DRAWN UNDER THE LETTER OF
        CREDIT."
  12
  OR
 
 (VI)           "WE
        HEREBY CERTIFY THAT THE LESSEE WAS REQUIRED TO DELIVER A QUALIFYING LETTER
        OF
        CREDIT ON OR BEFORE MAY 15, 2022, PURSUANT TO THAT CERTAIN MASTER LETTER
        AGREEMENT DATED AS
        OF JUNE _, 2007, THE LESSEE FAILED TO DELIVER SUCH LETTER OF CREDIT BY SUCH
        DATE
        AND HAS NOT DELIVERED SUCH LETTER OF CREDIT AS OF THE DATE OF THIS DRAWING,
        AND
        THE BENEFICIARY IS ENTITLED TO DRAW $___________, AN AMOUNT EQUAL TO THE
        AMOUNT
        OF SUCH LETTER OF CREDIT REQUIRED TO BE DELIVERED."
 
 (F)           such
        letter of credit shall provide that any draw will be honored in same day
        funds,
        wired in accordance with the Issuing Bank’s normal practices, but in no event no
        later than the next business day after the date of demand; and
 
 (G)           such
        letter of credit shall be transferable in its entirety, but not in part,
        on one
        or more occasions at no cost to Lessor or Beneficiary, and such transfer
        must be
        acknowledged by the Issuing Bank if requested by either Lessor or
        Beneficiary.”
 
 xx.           restating
        the definition of “Servicer” as follows:
 
 “**“Servicer”**
        shall mean Wachovia Bank, National Association, as successor to First Union
        National Bank, as servicer under the Indenture and its successors and
        assigns.”
 
 xxi.           deleting
        the definition of “TXU Guaranty Agreement.”
 
 (q)           Schedule
        9.1, part (b) is hereby modified by deleting the words “Guarantor (or Lessee
        if there is no Guarantor)” appearing in line 1 thereof and substituting in lieu
        thereof the word “Lessee”.
 
 (r)           Exhibit
        B, part (f) is hereby modified by deleting the words “[and the Guarantor]”
appearing in line 1 thereof.
 
 (s)           Any
        references in the Lease to “Guarantor” or “Guaranty” not hereinabove referenced
        are hereby deleted and the terms of the Lease are hereby accordingly modified
        to
        reflect the termination of the Guaranty and Guarantor.
 
 3.           Lessee’s
        Required Rating.  Lessee acknowledges that certain rights and
        obligations of Lessee under the Lease, as modified by this Amendment, are
        contingent upon whether Lessee has a Required Rating equal to or greater
        than
        the Trigger Rating.  Such rights and obligations include, without
        limitation, those included in Sections 7.1, 8.5, 8.6, 9.1 and 12.1 of the
        Lease,
        among others, and in certain definitions contained in Appendix A to the Lease
        including, among others, the definition of “Permitted Liens”.  Lessee
        further acknowledges that it has no rating from any NSRO, and that unless
        and
        until it has a Required Rating equal to or greater than the Trigger Rating
        from
        at least two (2) NSROs, all of such rights referenced
  13
  hereinabove
        shall not be available to Lessee and all of such obligations referenced
        hereinabove shall be imposed upon Lessee.
 
 4.           Representations
        and Warranties.  Lessee represents and warrants to Lessor that the
        following are true and correct as of the date of this Amendment:
 
 (a)           *Due
        Organization*.  Lessee is a corporation duly organized, validly
        existing and in good standing in the State of Texas and is qualified to do
        business in the State of Texas.  Lessee has the corporate power and
        authority to conduct its business as now conducted, to own or hold under
        lease
        its property, to lease the Property and to enter into and perform its
        obligations under the Lease, as amended by this Amendment, and the Master
        Letter
        Agreement. Lessee is duly qualified to do business and is in good standing
        as a
        foreign corporation in any jurisdiction where the failure to so qualify would
        have a material adverse effect on its ability to perform its obligations
        under
        the Lease, as amended by this Amendment, and the Master Letter
        Agreement.
  (b)           *Due
        Authorization; No Conflict*.  Each of the Lease, as amended by
        this Amendment, and the Master Letter Agreement has been duly authorized
        by all
        necessary corporate action on the part of Lessee and has been duly executed
        and
        delivered by Lessee, and the execution, delivery and performance thereof
        by
        Lessee will not, (i) require any approval of the stockholder of Lessee (except
        as heretofore obtained) or any approval or consent of any trustee or holder
        of
        any indebtedness or obligation of Lessee or of any Affiliate of Lessee, other
        than such consents and approvals as have been obtained, (ii) contravene any
        Applicable Law binding on Lessee or (iii) contravene or result in any breach
        of
        or constitute any default under Lessee’s charter or by-laws or other
        organizational documents, or any indenture, judgment, order, mortgage, loan
        agreement, contract, partnership or joint venture agreement, lease or other
        agreement or instrument to which Lessee is a party or by which Lessee is
        bound,
        or result in the creation of any Lien (other than pursuant to the Operative
        Documents) upon any of the property of Lessee.
  (c)           *Enforceability*.  Each
        of the Lease, as amended by this Amendment, and the Master Letter Agreement
        constitutes the legal, valid and binding obligation of Lessee, enforceable
        against Lessee in accordance with the terms thereof, except as enforceability
        may be limited by bankruptcy, moratorium, fraudulent conveyance, insolvency,
        general principles of equity or other similar laws affecting the enforcement
        of
        creditors’ rights in general.
  5.           Full
        Force and Effect.  Except as herein expressly amended, modified
        and supplemented, all of the terms, conditions and provisions of the Lease
        remain in full force and effect and are hereby ratified and confirmed in
        every
        respect.  Lessee takes the occasion of the execution of this Amendment
        to confirm that, to the best of Lessee’s knowledge:  (i) Lessor
        is not in default under the Lease and Lessor has fully and properly fulfilled
        all of its obligations under the Lease; (ii) Lessee has no dispute with
        respect to any payments of Base Rent and/or Supplemental Rent heretofore
        made by
        Lessee nor any other claims against Lessor under or in connection with the
        Lease
        or otherwise; and (iii) Lessee is in possession of the Property and is satisfied
        with the condition of the Property and that Lessor shall have no obligation
        to
        perform any work and/or installations, supply any materials or equipment
        and/or
        otherwise incur any cost or expense in order to prepare same for Lessee’s
        continued occupancy or otherwise.  Lessor
  14
  takes
        the occasion of the execution of this Amendment to confirm that, to the best
        of
        Lessor’s knowledge: (i) Lessee is not in default under the Lease and Lessee
        has fully and properly fulfilled all of its obligations under the Lease;
        and
        (ii) Lessor has no dispute with respect to any payments of Base Rent and/or
        Supplemental Rent heretofore made by Lessee nor any other claims against
        Lessee
        under or in connection with the Lease or otherwise.
 
 6.           Counterparts.  This
        Amendment may be executed in any number of counterparts, each of which shall
        be
        deemed an original and all of which counterparts together shall constitute
        one
        agreement with the same effect as if the parties had signed the same signature
        page.  Delivery of an executed counterpart of a signature page of this
        Amendment by facsimile shall be effective as delivery of a manually executed
        counterpart.
 
 7.           Effectiveness.  This
        Amendment shall be effective as of the date first above written.
 
 8.           Governing
        Law.  This Amendment shall be governed by, and construed in
        accordance with, the laws of the State of Texas and shall be binding upon
        the
        parties hereto and their respective permitted successors in interest and
        assigns.
 
 
 
 [REMAINDER
        OF PAGE INTENTIONALLY LEFT BLANK]
 
  15
  
 
 IN
        WITNESS WHEREOF, Lessor and Lessee have executed this Amendment as of date
        first
        above written.
  Lessor:
              U.S.
                  BANK, N.A. (as successor-in-interest to State Street Bank and Trust
                  Company of Connecticut, National Association), not in its individual
                  capacity but solely as owner trustee of ZSF/Dallas Tower
                  Trust
   
   By:  /s/
        EARL W. DENNISON
        JR.
   Name:
        EARL W. DENNISON
        JR.
   Title:  Vice
        President
   
   Lessee:                                             TXU
        PROPERTIES COMPANY
   
   By:  /s/
        ANTHONY
        HORTON
   Name:  Anthony
        Horton
   Title:  Treasurer
        and
        Assistant Secretary
   16