<PAGE>
                                                                 EXHIBIT 10.8(f)

                      SECOND AMENDMENT TO CREDIT AGREEMENT


         This SECOND AMENDMENT TO CREDIT AGREEMENT (this "Amendment") is entered
into effective as of November 3 2000, among WOODWARD MARKETING, L.L.C., a
Delaware limited liability company (the "Borrower"), BANK OF AMERICA, N. A.
("Bank of America"), as a Bank, as an Issuing Bank, and as Agent for the Banks,
and Woodward Marketing, Inc., Atmos Energy Marketing LLC, J. D. Woodward and
James Kifer (collectively the "Guarantors").

         WHEREAS, Borrower and Banks entered into that certain Credit Agreement,
dated to be effective as of August 9, 2000, as amended by that certain First
Amendment to Credit Agreement and Guaranty of Atmos Energy Marketing, LLC dated
as of September 29, 2000, (as amended the "Credit Agreement"); and

         WHEREAS, the Obligations (as defined in the Credit Agreement) were
guaranteed by the Guarantors pursuant to a Guaranty Agreement executed by each
of the Guarantors, in favor of the Banks (the "Guaranty Agreements"), dated as
of August 9, 2000; and

         WHEREAS, the Obligations are secured by security interests in the
Collateral (as defined in the Credit Agreement) granted to Bank pursuant to the
Security Agreements (as defined in the Credit Agreement) and pursuant to the
Nations Funds Security Agreement (as defined in the Credit Agreement), each
executed by Borrower (collectively, the "Security Agreements"); and

         WHEREAS, the parties hereto desire to amend the Credit Agreement as set
forth herein.

         NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained, Borrower, Bank of America and the Guarantors agree as follows:

         1. A definition "Collateralized L/C Line" is added to Section 1.01 of
the Credit Agreement, Certain Defined Terms, to read as follows:

                  "Collateralized L/C Line" means that certain uncommitted line
         of credit in an amount of up to $15,000,000.00 for the purpose of
         providing Cash Collateralized Letters of Credit with tenors not exceed
         90 days.

         2. The definition of "Line" set forth in Section 1.01 of the Credit
Agreement, Certain Defined Terms, is deleted in its entirety and replaced with
the following:

                  "Line" means any of the Borrowing Base Line, the
         Collateralized Line or the Overdraft Line.

         3. The definition of "Net Working Capital" set forth in Section 1.01 of
the Credit Agreement, Certain Defined Terms, is deleted in its entirety and
replaced with the following:



<PAGE>

                  "Net Working Capital" means the excess of Current Assets
         (minus all amounts due from employees, owners, Subsidiaries and
         Affiliates other than Accounts of Atmos Energy Corporation and its
         Subsidiaries and Affiliates permitted to be included as Eligible
         Accounts in the calculation of the Borrowing Base Advance Cap and minus
         the amount of any Cash Collateral pledged by the Borrower to secure a
         Letter of Credit under the Collateralized L/C Line) over Current
         Liabilities (excluding the current portion of Subordinated Debt), less
         investments in Capital Stock. In calculating Net Working Capital, the
         amount of Subordinated Debt excluded from liabilities in such
         calculation shall not exceed an amount equal to (i) 50% of the
         resultant Net Working Capital, plus (ii) the amount of the portion of
         Subordinated Debt the proceeds of which at such time are being used as
         Cash Collateral pledged by the Borrower to secure a Letter of Credit
         under the Collateralized L/C Line.

         4. The definition of "Tangible Net Worth" set forth in Section 1.01 of
the Credit Agreement, Certain Defined Terms, is deleted in its entirety and
replaced with the following:

                  "Tangible Net Worth" means (a) the sum of the Borrower's
         assets, as determined in accordance with GAAP, less (b) the sum of the
         Borrower's liabilities excluding Subordinated Debt, as determined in
         accordance with GAAP, less (c) all amounts due from employees, owners,
         Subsidiaries and Affiliates other than Accounts permitted to be
         included as Eligible Accounts in the calculation of the Borrowing Base
         Advance Cap, less (d) investments in Capital Stock, less (e) the
         intangible assets of the Borrower, as determined in accordance with
         GAAP, less (f) the amount of any Cash Collateral pledged by the
         Borrower to secure a Letter of Credit under the Collateralized L/C
         Line. In calculating Tangible Net Worth, the amount of Subordinated
         Debt excluded from liabilities in such calculation shall not exceed an
         amount equal to (i) 50% of the resultant Tangible Net Worth plus (ii)
         the amount of the portion of Subordinated Debt the proceeds of which at
         such time are being used as Cash Collateral pledged by the Borrower to
         secure a Letter of Credit under the Collateralized L/C Line.

         5. Section 3.01 (a) of Section 3.01 of the Credit Agreement, The Letter
of Credit Lines, is hereby deleted in its entirety and replaced with the
following:

                  3.01 The Letter of Credit Lines.

                           (a) On an uncommitted basis and on the terms and
         conditions set forth herein and if the Issuance of such Letter of
         Credit has been consented to by the Banks in their sole discretion (i)
         Issuing Bank agrees, (A) from time to time on any Business Day during
         the period from the Closing Date to the Expiration Date, to consider
         the Issuance of Letters of Credit for the account of the Borrower under
         the Borrowing Base Line or the Collateralized L/C Line and to consider
         whether to amend or renew Letters of Credit previously Issued by it, in
         accordance with Subsections 3.02(c) and 3.02(d), and (B) to honor
         drafts under the Letters of Credit; and (ii) the Banks shall
         participate in Letters of Credit Issued for the account of the
         Borrower; provided, however, the Declining Bank shall not have any
         obligation to and shall not be deemed to have participated in any



SECOND AMENDMENT TO CREDIT AGREEMENT - PAGE 2
<PAGE>

         Letters of Credit which are Issued on or after the Conversion to Single
         Funding Bank Date. Within the foregoing limits, and subject to the
         other terms and conditions hereof including, without limitation, the
         approval of the Banks in their sole discretion, the Borrower's ability
         to request that Issuing Bank Issue Letters of Credit shall be fully
         revolving, and, accordingly, the Borrower may, during the foregoing
         period, request that Issuing Bank Issue Letters of Credit to replace
         Letters of Credit which have expired or which have been drawn upon and
         reimbursed. The Existing L/Cs shall be deemed to be Letters of Credit
         Issued under this Agreement and shall be entitled to the benefits of
         this Agreement.

         6. Subsection 3.01 (b)(viii) of Section 3.01 of the Credit Agreement,
The Letter of Credit Lines, is hereby deleted in its entirety and replaced with
the following:

                  (viii) the amount of such requested Letter of Credit exceeds
         the Borrowing Base Advance Cap or Collateralized L/C Line limit.

         7. Section 3.07 of the Credit Agreement, Cash Collateral Pledge, is
hereby deleted in its entirety and replaced with the following:

         3.07     Cash Collateral Pledge. Upon the request of the Agent, (i) if
                  Issuing Bank has honored any full or partial drawing request
                  on any Letter of Credit and such drawing has resulted in an
                  L/C Borrowing hereunder, or (ii) if, as of the Expiration
                  Date, any Letters of Credit may for any reason remain
                  outstanding and partially or wholly undrawn, the Borrower
                  shall immediately Cash Collateralize the L/C Obligations in an
                  amount equal to such L/C Obligations. Upon the occurrence of
                  the circumstances described in Section 2.06 requiring the
                  Borrower to Cash Collateralize Letters of Credit, then, the
                  Borrower shall immediately Cash Collateralize the L/C
                  Obligations in an amount equal to the applicable excess. In
                  addition, the Borrower shall Cash Collateralize any Letter of
                  Credit to be Issued under the Collateralized L/C Line on or
                  before such Letter of Credit is actually Issued in an amount
                  equal to such Letter of Credit.

         8. Schedule 2.01 of the Credit Agreement is deleted in its entirety and
replaced with the Schedule 2.01 attached hereto.

         9. The Form of Notice of Borrowing (Letters Of Credit) attached to the
Credit Agreement is deleted in its entirety and replaced with Exhibit A, which
is attached hereto.

         10. Renewal; Continued Effect. Except as set forth above, the Credit
Agreement shall continue in full force and effect.

         11. Representations. To induce the Banks to enter into this Amendment,
Borrower ratifies and confirms each representation and warranty set forth in the
Credit Agreement as if such representations and warranties were made on even
date herewith, and further represents and warrants (a) that no material adverse
change has occurred in the financial condition or business prospects of Borrower
since the date of the last financial statements delivered to the Banks, (b)


SECOND AMENDMENT TO CREDIT AGREEMENT - PAGE 3
<PAGE>

that no Event of Default exists and no event or condition exists or has occurred
which with passage of time, or notice, or both, would become an Event of Default
(a "Default"), and (c) that Borrower is fully authorized to enter into this
Amendment. BORROWER ACKNOWLEDGES THAT THE CREDIT AGREEMENT PROVIDES FOR A CREDIT
FACILITY THAT IS COMPLETELY OPTIONAL ON THE PART OF THE BANK AND THAT THE BANK
HAS ABSOLUTELY NO DUTY OR OBLIGATION TO ADVANCE ANY REVOLVING LOAN OR TO ISSUE
ANY LETTER OF CREDIT. BORROWER REPRESENTS AND WARRANTS TO BANK THAT BORROWER IS
AWARE OF THE RISKS ASSOCIATED WITH CONDUCTING BUSINESS UTILIZING AN UNCOMMITTED
FACILITY.

         12. Conditions Precedent. As a condition to Bank of America entering
into this Amendment, no Default or Event of Default shall exist on the date
hereof, and Bank of America must have received executed originals of each of the
following documents and instruments, in form and substance satisfactory to Bank
of America:

                  (a) this Amendment, duly executed by Borrower;

                  (b) a Renewal Promissory Note in the amount of
         $115,000,000.00, duly executed by Borrower;

                  (c) an Amended and Restated Guaranty of each of the
         Guarantors; and

                  (d) such other documents or certificates as Bank of America
         may reasonably request.

         13. Ratification of Security Agreements. Borrower ratifies and confirms
the Security Agreements, and acknowledges and agrees that references to the
Credit Agreement in such Security Agreements are hereby amended to refer to the
Credit Agreement as amended by this Amendment and that in all other respects
such Security Agreements shall continue in full force and effect, and that
pursuant to such Security Agreements Borrower has granted and hereby confirms
and grants to Bank a continuing first and prior security interest in the
Collateral to secure payment and performance of all Obligations.

         14. Miscellaneous.

                  (a) Severability. In case any of the provisions of this
Amendment shall for any reason be held to be invalid, illegal, or unenforceable,
such invalidity, illegality, or unenforceability shall not affect any other
provision hereof, and this Amendment shall be construed as if such invalid,
illegal, or unenforceable provision had never been contained herein.

                  (b) Capitalized Terms. Except as otherwise defined herein,
capitalized terms shall have the meanings specified in the Credit Agreement.



SECOND AMENDMENT TO CREDIT AGREEMENT - PAGE 4
<PAGE>

                  (c) Execution in Counterparts. This Amendment may be executed
in any number of counterparts, all of which taken together shall constitute one
and the same instrument, and any party hereto may execute this Amendment by
signing one or more counterparts.

                  (d) Governing Law. This Amendment shall be construed in
accordance with and governed by the laws of the State of California (without
reference to principles of conflicts of laws), provided, however, that Bank
shall retain all rights under federal law.

                  (e) Rights of Third Parties. All provisions herein are imposed
solely and exclusively for the benefit of Borrower and Bank, and their permitted
successors and assigns, and no other Person shall be a direct or indirect legal
beneficiary of, or have any direct or indirect cause of action or claim in
connection with this Amendment or any of the other Loan Documents.

                  (f) COMPLETE AGREEMENT. THIS WRITTEN AMENDMENT AND THE OTHER
WRITTEN AGREEMENTS ENTERED INTO AMONG THE PARTIES REPRESENT THE FINAL AGREEMENT
AMONG THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO
UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]



SECOND AMENDMENT TO CREDIT AGREEMENT - PAGE 5
<PAGE>



               Executed as of the day and year first above written



                                            BORROWER:


                                            WOODWARD MARKETING, L.L.C.,
                                            a Delaware limited liability company



                                            By:      /s/ HENRY O. DRILLING
                                                   -----------------------------
                                            Name:    Henry O. Drilling
                                                   -----------------------------
                                            Title:   Sr. Vice President
                                                   -----------------------------


                                            BANKS:


                                            BANK OF AMERICA, N. A.,
                                            as Agent


                                            By:      /s/ IRENE C. RUMMEL
                                                   -----------------------------
                                            Name:    Irene C. Rummel
                                                   -----------------------------
                                            Title:   Vice President
                                                   -----------------------------


                                            BANK OF AMERICA, N. A.,
                                            as a Bank and Issuing Bank


                                            By:      /s/ IRENE C. RUMMEL
                                                   -----------------------------
                                            Name:    Irene C. Rummel
                                                   -----------------------------
                                            Title:   Vice President
                                                   -----------------------------

SIGNATURE PAGE - SECOND AMENDMENT TO CREDIT AGREEMENT
<PAGE>
                                           GUARANTORS:


                                           WOODWARD MARKETING, INC.


                                           By:      /s/ HENRY O. DRILLING
                                                  ------------------------------
                                           Name:    Henry O. Drilling
                                                  ------------------------------
                                           Title:   Sr. Vice President
                                                  ------------------------------


                                           ATMOS ENERGY MARKETING, LLC


                                           By:     /s/ LAURIE M. SHERWOOD
                                                  -----------------------------
                                           Name:   Laurie M. Sherwood
                                                  -----------------------------
                                           Title:  Vice President and Treasurer
                                                  -----------------------------


                                                   /s/ J. D. WOODWARD
                                           ------------------------------------
                                                   J. D. WOODWARD


                                                   /s/ JAMES KIFER
                                           ------------------------------------
                                                   JAMES KIFER



SIGNATURE PAGE - SECOND AMENDMENT TO CREDIT AGREEMENT
<PAGE>

                                  SCHEDULE 2.01

                              UNCOMMITTED LINE AND
                            UNCOMMITTED LINE PORTION
                         (EXCLUDING OVERDRAFT LINES AND
                                 SWAP CONTRACTS)


<Table>
<Caption>

                                                                                           Pro Rata
Line:                          Bank                             Dollar Amount               Share
-----                          ----                             -------------              --------
<S>                          <C>                                <C>                         <C>
Borrowing Base               Bank of America                    $100,000,000.00               100%
Line

Collateralized               Bank of America                    $ 15,000,000.00               100%
L/C Line
</Table>




SCHEDULE

<PAGE>
                                    EXHIBIT A

                           FORM OF NOTICE OF BORROWING
                               (LETTERS OF CREDIT)

                                     [DATE]

Bank of America, N. A.
333 Clay Street, Suite 4550
Houston, Texas 77002
Attention: Irene C. Rummel
Telephone: (713) 651-4921
Facsimile: (713) 651-4801

         Re:      Credit Agreement, dated to be effective as of August 9, 2000
                  (as amended or supplemented from time to time, the
                  "Agreement"), by and among Woodward Marketing, L.L.C. (the
                  "Borrower"), the banks that from time to time are parties
                  thereto, and Bank of America, N. A., as Agent

Ladies and Gentlemen:

         Reference is made to the Agreement (capitalized terms used herein that
are not defined shall have the respective meanings ascribed thereto in the
Agreement). The Borrower hereby gives notice of its intention to request the
[ISSUANCE, AMENDMENT, OR RENEWAL] of Letters of Credit as is further described
on the Letter of Credit Application attached hereto.

         The Borrower represents and warrants, as of the date hereof and as of
the date any Letter of Credit is Issued, amended or renewed, that (i) no Default
or Event of Default has occurred and is continuing on the date hereof, nor will
any thereof occur after giving effect to the Letters of Credit requested above;
and (ii) that neither the Borrowing Base Advance Cap nor the limit under the
Collateralized L/C Line will be exceeded after giving effect to the Letters of
Credit requested above.

                                           Very truly yours,

                                           WOODWARD MARKETING, L.L.C.,



                                           By:     /s/ HENRY O. DRILLING
                                              ----------------------------------
                                           Name:   Henry O. Drilling
                                                --------------------------------
                                           Title:  Responsible Officer



EXHIBIT A