<PAGE>

                                                                 Exhibit 10(f)

                               PURCHASE AGREEMENT


         PURCHASE AGREEMENT ("Agreement") dated as of April 26, 2004, by and
among each of the entities listed on the attached Schedule A (each a "Seller,"
and together the "Sellers"), and TXU Corp., a Texas corporation ("Purchaser").

                                  INTRODUCTION

         Each Seller is a Class B Preferred Member of TXU Energy Company LLC, a
Delaware limited liability company (the "Company"), and is a party to the Second
Amended and Restated Limited Liability Company Agreement of the Company, dated
as of July 1, 2003 (the "LLC Agreement"). Capitalized terms not otherwise
defined herein shall have the respective meanings set forth in the LLC
Agreement.

         Each Seller proposes to (i) sell, assign, and transfer its Class B
Preferred Membership Interests to the Purchaser in accordance with the terms and
subject to the conditions set forth in this Agreement and (ii) withdraw from the
Company as a Class B Preferred Member.

         The Purchaser proposes to (i) purchase, acquire, and accept each
Seller's Class B Preferred Membership Interests in accordance with the terms and
subject to the conditions set forth in this Agreement and (ii) be admitted to
the Company as the substituted Class B Preferred Member.

         NOW, THEREFORE, in consideration of the premises and agreements
contained herein, the parties hereto agree as follows:

                                   ARTICLE I.

                   SALE AND PURCHASE; termination of agreement

         SECTION 1.1.      Sale and Purchase of Interests.

             (a) Subject to the terms and conditions set forth herein, each
Seller hereby agrees to sell, assign, transfer, convey and deliver to Purchaser,
and Purchaser hereby agrees to purchase, acquire, and accept, each Seller's
Class B Preferred Membership Interests for an aggregate purchase price of
$614,323,158.74 plus accrued and unpaid dividends thereon from and including
April 1, 2004 through but excluding the Closing Date (as defined below);
provided that, if the Closing (as defined below) occurs after 12 P.M., Eastern
Daylight Time, on the Closing Date, the payment in respect of accrued and unpaid
dividends shall be through and including the Closing Date (the "Purchase
Price").

             (b) Subject to the terms and conditions of this Agreement, the sale
and purchase of the Class B Preferred Membership Interests contemplated by this
Agreement shall take place at a closing (the "Closing") to be held at or
directed from the offices of Thelen Reid & Priest LLP, at 10:00 A.M., Eastern
Daylight Time on April 26, 2004 or at such other place and or at such other time
or such other date as the Purchaser and Sellers shall mutually agree upon in
writing (the date on which the Closing takes place being the "Closing Date").

<PAGE>

             (c) At the Closing, the Sellers shall deliver, or cause to be
delivered, to the Purchaser, the Class B Preferred Membership Interest
Certificates evidencing the Sellers' Class B Preferred Membership Interests.

             (d) At the Closing, the Purchaser shall deliver, or cause to be
delivered, (i) to the Sellers, the Purchase Price by wire transfer in
immediately available funds to an account designated in writing by the Sellers
to the Purchaser not later than one business day prior to the Closing Date,
(ii) to the Secretary of the Company, a duly executed Class B Joinder
substantially in the form attached to the LLC Agreement and (iii) to the
Sellers, reasonably satisfactory evidence of compliance with Sections 1.5 and
1.6 hereof.

         SECTION 1.2. Assignment of Other Rights. Effective upon the Closing,
each Seller hereby assigns, transfers, conveys and delivers to Purchaser, and
Purchaser hereby accepts such assignment, transfer, conveyance and delivery of,
any and all rights that the Seller may have under and in accordance with the
Assignment, Assumption and Waiver Agreement dated as of December 19, 2002 among
UXT Holdings LLC ("UXTH"), UXT Intermediary LLC ("UXTI"), Sellers, Purchaser,
the Company and Berkshire Hathaway Inc., as amended (the "Assignment and
Assumption Agreement), the Purchase Agreement dated as of November 18, 2002
among UXTH, UXTI, Purchaser and the Company (the "Purchase Agreement"), the
Exchange Agreement and the Registration Rights Agreement dated as of November
22, 2002 among UXTH, UXTI and Purchaser, as amended (the "Registration Rights
Agreement").

         SECTION 1.3. Assumption. Effective upon the Closing, Purchaser hereby
assumes any and all obligations of each Seller in respect of its Class B
Preferred Membership Interests under the LLC Agreement, Class B Preferred
Membership Interest Certificate and the Delaware Act.

         SECTION 1.4. Release of Sellers. Effective upon the Closing and the
delivery by Purchaser of the Class B Joinder to the Secretary of the Company,
pursuant to the terms of the LLC Agreement, each Seller shall no longer be a
member of the Company in accordance with Section 18-702(b)(3) of the Delaware
Act and shall have no further duty, liability, or obligation under the LLC
Agreement and the Class B Preferred Membership Interest Certificate.

         SECTION 1.5. Withdrawal and Admission. Effective at the Closing,
assuming the delivery by Purchaser of the Class B Joinder to the Secretary of
the Company, pursuant to the terms of the LLC Agreement, the Company shall (i)
cause the Secretary of the Company to adjust the Class B Preferred Members
Schedule, and (ii) cause the Sellers' Class B Preferred Membership Interest
Certificates to be cancelled and shall issue new Class B Preferred Membership
Interest Certificates to Purchaser, in each case, to reflect the transaction
contemplated by this Agreement and Purchaser shall be admitted to the Company as
a substituted Class B Preferred Member in respect of the Class B Preferred
Membership Interests of each Seller acquired hereunder and, immediately
thereafter, each Seller shall be withdrawn from the Company as a Class B
Preferred Member.

                                       2
<PAGE>

         SECTION 1.6. Effect of Withdrawal and Substitution. Effective at the
Closing, assuming the delivery by Purchaser of the Class B Joinder to the
Secretary of the Company, pursuant to the terms of the LLC Agreement, the
Company shall cause the Capital Account of each Seller to be transferred to
Purchaser. After the Closing, the portion of the Net Income or Net Losses of the
Company and the portions of all other items of income, gain, loss, deduction, or
credit allocable to the Class B Preferred Membership Interests of each Seller on
or after such date shall be credited or charged, as the case may be, to
Purchaser and not to Seller, as provided in Section 8.05(b) of the LLC
Agreement. Purchaser shall be entitled to all distributions or payments in
respect of its Class B Preferred Membership Interests (not including the payment
to Sellers under Section 1.1 hereof) made after the Closing.

         SECTION 1.7. Acknowledgement of Sellers. The Sellers hereby expressly
acknowledge and agree that the Sellers shall have no further rights under the
LLC Agreement, the Class B Preferred Membership Interest Certificates, the
Assignment and Assumption Agreement, the Purchase Agreement, the Exchange
Agreement and the Registration Rights Agreement; provided, however, that the
rights of the Sellers and their respective Indemnitees pursuant to Article VI of
the Class B Preferred Membership Interest Certificates shall survive the Closing
indefinitely.

         SECTION 1.8. Termination of Agreement. This Agreement may be terminated
by either Purchaser or the Sellers at any time after 5 P.M., Eastern Daylight
Time, on Monday, April 26, 2004 if the Closing has not occurred prior to such
time. Termination of this Agreement pursuant to this Section 1.8 shall be
effective upon delivery of a written notice thereof to the non-terminating
party. If terminated pursuant to this Section 1.8, this Agreement shall become
wholly void and of no further force and effect without liability to Purchaser or
the Sellers or any of their respective Subsidiaries or Affiliates or any
officers, directors, employees, agents, advisors or other representatives of any
thereof; except that the rights and obligations of the parties under this
Section 1.8 and Article VI shall remain in full force and effect; provided,
however, that nothing contained in this Section 1.8 shall be deemed to release
any party from any liability for any willful breach of its obligations under
this Agreement in any material respect.

                                   ARTICLE II.

                    REPRESENTATIONS AND WARRANTIES OF SELLER

         Each Seller represents and warrants to Purchaser as follows:

         SECTION 2.1. Authority; Validity. Seller has all requisite power and
authority to execute, deliver, and perform this Agreement. The execution and
delivery of this Agreement by Seller, the performance by it of its obligations
hereunder, and the consummation of the transactions contemplated hereby have
been duly authorized by all requisite action on the part of Seller. This
Agreement has been duly executed and delivered by Seller, and (assuming due
authorization, execution, and delivery by Purchaser), this Agreement constitutes
a legal, valid, and binding obligation of Seller, enforceable against Seller, in
accordance with its terms.

         SECTION 2.2. Ownership Interest. Seller is the sole owner of the Class
B Preferred Membership Interests listed on Schedule A, free and clear of all
Claims. For purposes of this Agreement, "Claims" shall mean any security

                                       3
<PAGE>

interest, pledge, hypothecation, mortgage, lien (including, without limitation,
environmental and tax liens), violation, charge, lease, license, encumbrance,
servient easement, adverse claim, reversion, reverter, preferential arrangement,
restrictive covenant, condition or restriction of any kind, including without
limitation, any restriction on the use, voting, transfer, receipt of income or
other exercise of any attributes of ownership.

         SECTION 2.3. Transfer of Interest. Upon consummation of the
transactions contemplated by this Agreement, Seller will transfer good and
marketable title to its Class B Preferred Membership Interests to Purchaser,
free and clear of all Claims (other than Claims created by or through Purchaser
or its Affiliates).

         SECTION 2.4. No Conflicts; Consents. The execution, delivery, and
performance of this Agreement by the Seller and the consummation of the
transactions contemplated hereby do not and will not (i) violate, conflict with,
or result in a breach of any provision of the organizational documents of the
Seller, (ii) conflict with or result in a default (or give rise to any right of
termination, cancellation, or acceleration) under any of the terms, conditions,
or provisions of any note, bond, lease, mortgage, indenture, permit, agreement,
or other instrument or obligation to which the Seller is a party, or by which
the Seller or any of its properties or assets may be bound or affected, (iii)
conflict with or violate any statute, ordinance, law, rule, regulation, or
governmental order applicable to the Seller or its properties or assets, or (iv)
result in the creation or imposition of any Claim upon any property or assets
used or held by the Seller. No waiver, consent, or approval by, any notification
or filing with, or any other action by, any Person is required in connection
with the execution, delivery, and performance by the Seller of this Agreement or
the consummation of the transactions contemplated hereby.

                                    ARTICLE III.

                   REPRESENTATIONs AND WARRANTIES OF PURCHASER

         The Purchaser represents and warrants to Sellers as follows:

         SECTION 3.1. Existence and Power. Purchaser is a corporation duly
organized, validly existing, and in good standing under the laws of the
jurisdiction of its incorporation and has all requisite corporate power and
authority to execute, deliver, and perform this Agreement, to carry out its
obligations hereunder, and to consummate the transactions contemplated hereby.

         SECTION 3.2. Authority; Validity. The execution and delivery of this
Agreement by Purchaser, the performance by it of its obligations hereunder, and
the consummation of the transactions contemplated hereby have been duly
authorized by all requisite action on the part of Purchaser. This Agreement has
been duly executed and delivered by Purchaser, and (assuming due authorization,
execution, and delivery by the Sellers) this Agreement constitutes a legal,
valid, and binding obligation of Purchaser enforceable against Purchaser in
accordance with its terms.

         SECTION 3.3. No Conflicts; Consents. The execution, delivery, and
performance of this Agreement by Purchaser and the acknowledgement by the
Company and the consummation of the transactions contemplated hereby and thereby

                                       4
<PAGE>

do not and will not (i) violate, conflict with, or result in a breach of any
provision of the articles or certificate of incorporation or other
organizational documents or by-laws of Purchaser or the Company, (ii) conflict
with or result in a default (or give rise to any right of termination,
cancellation, or acceleration) under any of the terms, conditions, or provisions
of any note, bond, lease, mortgage, indenture, permit, agreement, or other
instrument or obligation to which Purchaser or the Company is a party
(including, in each case, by way of cross-default from any such obligation of a
material subsidiary), or by which Purchaser or the Company or any of their
properties or assets may be bound or affected, (iii) conflict with or violate
any statute, ordinance, law, rule, regulation, or governmental order applicable
to Purchaser or the Company or their properties or assets, or (iv) result in the
creation or imposition of any Claim upon any property or assets used or held by
Purchaser or the Company. No waiver, consent, or approval by, any notification
or filing with, or any other action by, any Person (other than as contemplated
by this Agreement) is required in connection with the execution, delivery, and
performance by Purchaser of this Agreement or the consummation of the
transactions contemplated hereby.

                                   ARTICLE IV.

                  REPRESENTATIONS AND WARRANTIES OF THE COMPANY

         The Company represents and warrants to Sellers and Purchaser as
follows:

         SECTION 4.1. Existence and Power. The Company is a limited liability
company duly formed, validly existing, and in good standing under the laws of
the jurisdiction of its incorporation and has all requisite corporate or similar
power and authority to execute, deliver, and perform this Agreement, to carry
out its obligations hereunder, and to consummate the transactions contemplated
hereby.

         SECTION 4.2. Authority. The execution and delivery of this Agreement
by the Company, the performance by it of its obligations hereunder, and the
consummation of the transactions contemplated hereby have been duly authorized
by all requisite action on the part of Company.

         SECTION 4.3. Validity of Transfers. The Transfers and related
transactions contemplated by this Agreement do not violate or conflict with the
LLC Agreement, including without limitation Section 11.06(b) thereof.

                                   ARTICLE V.

                              ADDITIONAL AGREEMENT

         SECTION 5.1. Transfer as Purchase and Sale. Purchaser, the Company and
Sellers hereby agree to treat the Transfer of each Seller's Class B Preferred
Membership Interests to Purchaser as contemplated in this Agreement as a
purchase and sale under Sections 741 and 1001 of the Code and not as a
retirement under Section 736 of the Code.

                                       5
<PAGE>

                                   ARTICLE VI.

                                  MISCELLANEOUS

         SECTION 6.1. Further Assurances. Each of the parties hereto and the
Company shall execute such other documents and instruments of transfer or
assignment and do such other acts or things as may be reasonably required or
desirable to carry out the intent of the parties and the Company hereunder and
the provisions of this Agreement and the transactions contemplated hereby.

         SECTION 6.2. Notices, etc. All notices and other communications
provided for hereunder shall be in writing and shall be delivered in person or
by courier service, with written receipt of acceptance returned to sender, or
via certified or registered mail, return receipt requested (postage and charges
prepaid), or by telecopier to each of the parties at the address or telecopier
number set forth in Section 13.01 of the LLC Agreement (with respect to
Purchaser and the Company) and on the Class B Preferred Members Schedule (with
respect to the Sellers) or telecopier number as shall be designated by a party
in a written notice to the other parties. All such notices and communications
shall, when mailed or telecopied, be effective when received at the relevant
address. Telecopied communications must be followed by a hard copy sent by
registered or certified mail, postage and charges prepaid.

         SECTION 6.3. Amendments; Waivers. This Agreement may be amended or
modified, and any of the terms or conditions hereof may be waived, only by a
written instrument executed by the parties hereto, including the Company with
respect to Sections 1.4, 1.5, 1.6, 1.7, 5.1 and Article VI and any other
provision of this Agreement that directly relates to the Company, or in the case
of a waiver, by the party waiving compliance. Any waiver by any party of any
condition, or of the breach of any provision or term contained in this
Agreement, in any one or more instances, shall not be deemed to be nor construed
as a furthering or continuing waiver of any such condition, or of the breach of
any other provision or term of this Agreement.

         SECTION 6.4. Costs and Expenses. Each party hereto, including the
Company, agrees to pay its own costs and expenses with respect to the
transactions contemplated by this Agreement.

         SECTION 6.5. No Third-Party Beneficiaries. This Agreement is for the
sole benefit of the parties hereto, the Company and their successors and assigns
and, with respect to Section 1.7 hereof, the Sellers' respective Indemnitees,
and nothing herein, express or implied, shall give or be construed to give any
Person other than the parties hereto, the Company, such successors and assigns
and such Indemnitees any legal or equitable rights hereunder.

         SECTION 6.6. Governing Law/Consent to Jurisdiction. This Agreement
shall be governed by, and construed in accordance with, the laws of the State
of New York. Each of the parties hereto hereby (i) submits to the exclusive
jurisdiction of any state or federal court sitting in the Borough of Manhattan
of the City of New York for the purpose of any action arising out of or relating
to this Agreement brought by any party hereto, and (ii) irrevocably waives, and
agrees not to assert by way of motion, defense or otherwise, in any such action,
any claim that it is not subject personally to the jurisdiction of the
above-names courts, that its property is exempt or immune from attachment or
execution, that the action is brought in an inconvenient forum, that the venue
of the action is improper, or that this Agreement or the transactions
contemplated by this Agreement may not be enforced in or by any of the
above-named courts.

                                       6
<PAGE>

         SECTION 6.7. WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO,
INCLUDING THE COMPANY, HEREBY WAIVES TO THE EXTENT PERMITTED BY APPLICABLE LAW
ANY RIGHT IT MAY HAVE TO A TRIAL BY JURY WITH RESPECT TO ANY LITIGATION
DIRECTLY OR INDIRECTLY ARISING OUT OF, UNDER OR IN CONNECTION WITH THIS
AGREEMENT OR THE TRANSACTIONS CONTEMPLATED BY THIS AGREEMENT.

         SECTION 6.8. Counterparts. This Agreement may be signed in any number
of counterparts, each of which shall be deemed an original and, when taken
together, shall constitute one agreement.

         SECTION 6.9. Headings. Section headings in this Agreement are included
herein for convenience of reference only and shall not constitute a part of this
Agreement for any other purpose.

                      [Signatures follow on separate pages]




                                       7
<PAGE>



         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the date first above written.

                              SELLERS:


                              BENJAMIN MOORE PENSION


                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory



                              THE BUFFALO NEWS OFFICE PENSION PLAN



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory



                              THE BUFFALO NEWS EDITORIAL PENSION PLAN



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory



                              CORNHUSKER CASUALTY COMPANY



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory


                                       8
<PAGE>


                              FLIGHTSAFETY INTERNATIONAL INC.
                              RETIREMENT INCOME PLAN



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory



                              FRUIT OF THE LOOM PENSION TRUST



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory



                              GEICO CORPORATION PENSION PLAN TRUST



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory



                              GOVERNMENT EMPLOYEES INSURANCE COMPANY



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                     Name: Mark D. Millard
                                     Title: Authorized Signatory


                                       9
<PAGE>



                              JOHNS MANVILLE CORPORATION MASTER PENSION TRUST



                              By: /s/ Mark D. Millard
                                  --------------------------------------------
                                   Name: Mark D. Millard
                                   Title: Authorized Signatory



                              JUSTIN BRANDS, INC. UNION PENSION PLAN
                              AND JUSTIN BRANDS, INC. PENSION PLAN & TRUST



                              By: /s/ Mark D. Millard
                                 --------------------------------------------
                                   Name: Mark D. Millard
                                   Title: Authorized Signatory



                             ACME BRICK COMPANY PENSION TRUST



                             By: /s/ Mark D. Millard
                                ----------------------------------------------
                                   Name: Mark D. Millard
                                   Title: Authorized Signatory



                             SCOTT FETZER COMPANY COLLECTIVE INVESTMENT TRUST



                             By: /s/ Mark D. Millard
                                 ---------------------------------------------
                                 Name: Mark D. Millard
                                 Title: Authorized Signatory


                                       10
<PAGE>

                             PURCHASER:

                             TXU CORP.



                             By:  /s/ Kirk R. Oliver
                                  --------------------------------------------
                                  Name: Kirk R. Oliver
                                  Title: Treasurer & Assistant Secretary



                                       11
<PAGE>


         By signing below, the undersigned hereby acknowledges, and subject to
the receipt from Purchaser of the Class B Joinder and, pursuant to the terms of
the LLC Agreement, agrees to Sections 1.4, 1.5, 1.6, 1.7, 5.1 and Article VI of
this Agreement.



                             TXU ENERGY COMPANY LLC



                             By:  /s/ Kirk R. Oliver
                                 ------------------------------------------
                                 Name: Kirk R. Oliver
                                Title: Treasurer & Assistant Secretary





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<PAGE>
<TABLE>
<CAPTION>
                                                                                                      Schedule A
                                                                                                      ----------



                                                                          Class B Preferred Membership Interests
                       Seller                         Certificate #               (by liquidation amount)
-------------------------------------------          --------------       ---------------------------------------
<S>                                                          <C>                       <C>
Benjamin Moore Pension                                       3                         $15,900,000

The Buffalo News Office Pension Plan                         4                          $4,200,000

The Buffalo News Editorial Pension Plan                      5                          $6,400,000

Cornhusker Casualty Company                                  6                         $25,000,000

FlightSafety International Inc. Retirement                   7                          $7,400,000
   Income Plan

Fruit of the Loom Pension Trust                              8                         $13,500,000

GEICO Corporation Pension Plan Trust                         9                         $57,000,000

Government Employees Insurance                              10                         $29,000,000
   Company

Johns Manville Corporation Master                           11                         $70,000,000
   Pension Trust

Justin Brands, Inc. Union Pension Plan                      12                          $4,300,000
   and Justin Brands, Inc. Pension Plan
   and Trust

Acme Brick Company Pension Trust                            13                         $10,300,000

Scott Fetzer Company Collective                             14                          $7,000,000
   Investment Trust

</TABLE>

                                      A-1