Exhibit
      10.4






**PERFORMANCE
          UNIT AWARD AGREEMENT**
  THIS
          PERFORMANCE UNIT AWARD AGREEMENT (“Award Agreement”) is made and entered
          effective as of the 1 st day of April, 2007, by and between TXU CORP., a Texas corporation (“Company”),
          and «Participant» (“Participant”).
  WHEREAS,
          the Company has adopted the TXU Corp. 2005 Omnibus Incentive Plan (“Plan”), the
          purpose of which is to assist the Company in attracting, retaining and
          motivating executive officers and other key employees essential to the
          success
          of the Company through performance-related incentives linked to long-range
          performance goals; and
  WHEREAS,
          the Plan provides for various types of stock and cash based incentive
          compensation awards, as well as covered employee annual incentive awards
          to be
          made to eligible Employees; and
  WHEREAS,
          in accordance with the provisions of the Plan, the Participant has been
          designated as being eligible to receive an award of performance units (“Award”)
          payable in, and valued on the basis of, Company common stock as described
          herein
          (“Performance Units”) in order to carry out the intent and purposes of the Plan
          all as set forth herein; and
  WHEREAS,
          this Award Agreement constitutes part of a prospectus covering the Performance
          Units which are being awarded hereunder, where Company common stock constituting
          the value of the Award has been registered under the Securities Act of
          1933;
          and
  WHEREAS,
          Company and Participant agree that this Award Agreement is subject to the
          terms
          and conditions of the Merger Agreement, dated February 25, 2007, among
          TXU Corp.
          and Texas Energy Future Holdings Limited Partnership (“Merger Agreement”) and no
          term(s) or condition(s) of this Award Agreement is intended to, nor does
          it,
          alter any of the terms and conditions of the Merger Agreement; and
  WHEREAS,
          Company and the Participant also agree that if the merger, as described
          in the
          Merger Agreement, closes as set forth in the Merger Agreement (“Closing”), this
          Award Agreement will be modified automatically, as provided for
          herein.
  NOW
          THEREFORE, in consideration of the covenants herein set forth and other
          good and
          valuable consideration, the receipt and sufficiency of which are hereby
          acknowledged, the parties agree as follows:
  1.  Award
          of Performance Units .
          The Company hereby awards to Participant «Award» Performance Units, each such Performance Unit having a value equal to one
          share
          of the Company’s common stock, without par value (“Company Stock”), pursuant to
          the terms and subject to the conditions and restrictions set forth
          herein.
  2.  Performance
          Period and Adjustment of Number of Performance Units .
          The award of Performance Units shall be subject to comparative total shareholder
          return performance criteria as described below. For purposes of determining
          the
          adjustments to the number of Performance Units under this section, the
          Target
          Award (“Target”) shall be the number of Performance Units awarded under Section
          1 hereof plus any additional Performance Units added
   
  to
          this Award during the Performance Period by virtue of the “dividends” provisions
          of Section 6 hereof.
  (a)  During
          the period commencing April 1, 2007 and ending at either March 31, 2010
          or at
          Closing, if it occurs before March 31, 2010 (“Performance Period”), the
          Company’s financial performance, measured in terms of total shareholder return,
          shall be compared to, and measured against, the performance of other companies
          within a peer group consisting of the Standard & Poor’s 500 Electric
          Utilities Index (“Peer Group”). Upon the expiration of the Performance Period,
          the Committee will compare the Company’s total shareholder return with the total
          shareholder return of the companies within the Peer Group and determine
          the
          Company’s percentile ranking within the Peer Group during the Performance
          Period.
  (b)  Based
          on the Company’s performance within the Peer Group during the Performance
          Period, the number of Performance Units shall be adjusted in accordance
          with the
          methodology set forth below. For purposes of this Agreement, the term
          Performance Units will include such adjusted number of Performance
          Units.
  
 **Performance
                    Levels**
                **Total
                    Shareholder Return Ranges**
                **Initial
                    Number of Performance Units Adjusted by the
                    Following:**Maximum
                81st
                    Percentile & Above
                Maximum
                    payout (200% of Target)150%
                    of Target
                71st
                    - 80.99thPercentiles
                Interpolate
                    between 150% of Target & Maximum (150% & 200% of
                    Target)125%
                    of Target
                61st
                    - 70.99thPercentiles
                Interpolate
                    between 125% of Target & 150% of TargetTarget
                51st
                    - 60.99thPercentiles
                Interpolate
                    between 100% of Target & 125% of TargetMinimum
                41st
                    - 50.99thPercentiles
                Interpolate
                    between Minimum & Target (50% to 100% of Target)Zero
                40.99thPercentile & Below
                No
                    payout
  3.  Vesting,
          Valuation and Payment of Award .
  (a)  The
          Performance Units, as adjusted in accordance with the provisions of Sections
          2(a) and 2(b) above, shall become vested upon the expiration of the Performance
          Period, and shall be valued as of the date of the Committee’s determination of
          the Company’s performance within the Peer Group during the Performance Period
          (“Valuation Date”), at which time the adjustment described in Section 2(b) shall
          be made. In calculating the value of the Award, each Performance Unit will
          equal
          the value of the average of the high and low trading price of one (1) share
          of
          Company Stock on the Valuation Date.
  (b)  This
          Award shall be paid to Participant in the form of shares of Company Stock
          having
          an aggregate value equal to the value of the Award determined in accordance
          with
          the valuation methodology described in Section 3(a) above. Such distribution
          of
          Company Stock, net of applicable tax withholding, shall be made as soon
          as
          reasonably practicable (and in any event within forty-five (45) days) following
          the Valuation Date. The Valuation Date and the
   2
  distribution
          of the Company Stock shall occur within the same calendar year as the expiration
          of the Performance Period.
  (c)  Notwithstanding
          any provision of Sections 3(a) and 3(b) to the contrary, at the Closing
          of the
          merger described herein, the Award will immediately vest. The Award will
          be paid
          to the Participant in cash and valued at the Closing price set by the Merger
          Agreement. The Award will be paid to Participant as soon as reasonably
          practicable, at the end of the three-year performance period of March 31,
          2010.
  4.  Forfeiture
          of Performance Units Under Certain Circumstances.
  (a)  Forfeiture
          Upon Termination of Employment under Certain Circumstances .
          If Participant’s employment with the Company shall, at any time during the
          Performance Period, be terminated by the Company for Cause (as defined
          in that
          certain Employment Agreement between the Company and Participant dated
          as of «Date_of_Emp_Agt» ,
          (“Employment Agreement”)) or by Participant without Good Reason (as defined in
          the Employment Agreement), this Award and all Performance Units covered
          hereunder shall immediately be forfeited by Participant. Upon such forfeiture,
          Participant shall have no further right, title or interest in or to this
          Award
          or any Performance Units.
 
 (b)  Continuation
          Following Termination of Employment Under Certain Circumstances .
          If Participant’s employment with the Company shall, at any time during the
          Performance Period, be terminated under circumstances which, pursuant to
          the
          terms and conditions of the Employment Agreement, do not result in the
          forfeiture of this Award, this Award shall not forfeit and shall be paid
          at the
          time and in the amount provided for in, and subject to the terms and conditions
          of, this Agreement, consistent with the provisions of the Employment
          Agreement.
 
 (c)  Consistency
          With Terms of Employment Agreement .
          The terms of this Section 4 are intended to be consistent with the terms
          of the
          Employment Agreement regarding the forfeiture or the continuation of this
          Award
          under the various circumstances described in the Employment Agreement,
          and this
          Section 4 shall be so construed. In the event of any conflict between the
          provisions of this Agreement and the Employment Agreement relating to the
          terms
          of this Award, the provisions of the Employment Agreement will
          control.
 
 5.  Nontransferability .
          No right of the Participant hereunder may be sold, transferred, pledged,
          assigned or otherwise alienated, hypothecated or disposed of and any attempt
          to
          effect any such sale, transfer, pledge, assignment or disposition shall
          be null
          and void and of no force or effect whatsoever.
  6.  Dividends .
          If and when dividends are paid on Company Stock, the number of Performance
          Units
          covered by the Award will be increased by: (a) in the case of a dividend
          paid in
          cash, the number of full and fractional shares of Company Stock which could
          have
          been purchased with the amount of the dividend that would have been paid
          had
          each Performance Unit been one (1) share of Company Stock and as if the
          Performance Units had been invested in the TXU Direct Stock Purchase and
          Dividend Reinvestment Plan; or (b) in the case of a dividend paid in stock,
          the
          number of full and fractional shares of Company Stock which would have
          been
   3
  distributed
          in connection with such dividend had each Performance Unit been one (1)
          share of
          Company Stock.
  7.  Capital
          Adjustments .
          The number of Performance Units covered by this Award shall be subject
          to
          adjustment, if any, as the Committee deems appropriate upon the occurrence
          of
          certain events and in the manner as described in Section 4.4 of the
          Plan.
  8.  No
          Right to Employment .
          Neither this Award Agreement, nor the Award of the Performance Units provided
          for herein, shall be construed as giving Participant any right of employment
          or
          continued employment with the Company or any affiliated entity of the
          Company.
  9.  Withholding .
          Participant understands and agrees that the Company shall deduct or withhold
          any
          taxes required by law to be withheld in connection with the Award provided
          for
          herein.
  10.  Subject
          to Plan .
          The Award of the Performance Units and this Award Agreement are subject
          to all
          of the terms and conditions of the Plan (as the Plan may be amended from
          time to
          time). In the event of any conflict between the terms and conditions of
          the Plan
          and those set forth herein, other than those terms or conditions relating
          to the
          Merger Agreement or the Employment Agreement, the terms and conditions
          of the
          Plan shall control.
  11.  Governing
          Law .
          This Award Agreement shall be governed, construed, interpreted and administered
          in accordance with the laws of the State of Texas. This Award Agreement
          is being
          entered into and shall be performed, in whole or in part, in Dallas County,
          Texas, and the parties hereby acknowledge and agree that, in any dispute
          involving this Award Agreement, venue shall be in the appropriate court
          in
          Dallas County, Texas.
  12.  Severability .
          In the event any provision of this Award Agreement shall be held invalid,
          illegal or unenforceable, in whole or in part, for any reason, such
          determination shall not affect the validity, legality or enforceability
          of any
          remaining provision or portion of provision, which shall remain in full
          force
          and effect as if this Award Agreement had not contained the invalid, illegal
          or
          unenforceable provision or portion.
  13.  Amendment .
          The Committee shall have the right at any time and from time to time, without
          the approval or consent of Participant, to amend this Award Agreement if
          additions and/or changes are made to the Internal Revenue Code of 1986,
          as
          amended, any federal or state securities law, or other law or regulation
          applicable to the Award provided for herein. The Committee shall have the
          right
          at any time, and from time to time, to amend this Award Agreement for any
          other
          reason with the consent of Participant.
  14.  Award
          Not Benefit Eligible .
          Participant understands and agrees that the Award of Performance Units
          shall be
          considered as extraordinary, special incentive compensation and will not
          be
          included as “earnings,” “wages,” “salary” or “compensation” in any pension,
          welfare, life insurance, or other employee benefit plan or arrangement
          of the
          Company.
  15.  Notices .
          Any notice required or permitted hereunder shall be given in writing and
          shall
          be deemed effectively given upon personal delivery or upon deposit in the
          United
          States
   4
  Post
          Office, by registered or certified mail, with postage and fees prepaid,
          addressed to the other party hereto at the address shown opposite his,
          her or
          its signature below or at such other address as such party may designate
          by not
          less than five (5) days’ advance written notice to the other party
          hereto.
  16.  Further
          Assurances .
          The parties agree to execute such further instruments and to take such
          further
          action as may reasonably be necessary to carry out the intent of this Award
          Agreement.
  17.  Entire
          Agreement .
          This Award Agreement constitutes the entire agreement of the parties with
          respect to the subject matter hereof.
  18.  Binding
          Effect .
          This Award Agreement shall be binding upon and inure to the benefit of
          the
          parties hereto and their respective successors, heirs, executors,
          administrators, guardians and personal representatives. Nothing in this
          Award
          Agreement shall be construed to give any person or entity other than the
          parties
          hereto and their respective successors any legal or equitable right, remedy
          or
          claim under this Award Agreement.
  19.  Capitalized
          Terms .
          Unless otherwise defined herein, each of the capitalized terms used herein
          shall
          have the meaning given to such term in the Plan.
  20.  Headings .
          Headings of the several sections of this Award Agreement are inserted for
          convenience only and shall not control or affect the meaning or construction
          of
          any of the provisions hereof.
  IN
          WITNESS WHEREOF, the parties hereto have entered into this Award
          Agreement.
  **TXU
                    CORP.**Address:
                
                By:
                /s/
                    M. Riz Chand1601
                    Bryan Street
                
                
                M.
                    Riz ChandDallas,
                    TX 75201
                
                
                Senior
                    Vice PresidentAttn:
                    Corporate Secretary
                
                
                Human
                    Resources**PARTICIPANT**Address:««Participant»»
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