<PAGE>

                                                                  EXHIBIT 10.4.2

                  FIRST AMENDMENT TO RESTATED CREDIT AGREEMENT

         THIS FIRST AMENDMENT TO RESTATED CREDIT AGREEMENT (hereinafter referred
to as the "First Amendment") executed as of the 1st day of April, 2003, by and
among GREAT LAKES ENERGY PARTNERS, L.L.C., a Delaware limited liability company
(hereinafter referred to as "Borrower") and BANK ONE, NA (successor by merger to
Bank One, Texas, N.A.) ("Bank One"), JPMORGAN CHASE BANK ("Chase"), THE BANK OF
NOVA SCOTIA ("Scotiabank"), BANK OF SCOTLAND ("BOS"), CREDIT LYONNAIS NEW YORK
BRANCH ("CL"), FORTIS CAPITAL CORP. ("Fortis"), THE FROST NATIONAL BANK
("Frost"), UNION BANK OF CALIFORNIA, N.A. ("Union"), COMERICA BANK-TEXAS
("Comerica") and NATEXIS BANQUES POPULAIRES ("Natexis") and each of the
financial institutions which is a party hereto (as evidenced by the signature
pages to this Agreement) or which may from time to time become a party hereto
pursuant to the provisions of Section 28 of the hereinafter defined Credit
Agreement or any successor or assignee thereof (hereinafter collectively
referred to as "Lenders", and individually, "Lender"), Bank One, as
Administrative Agent, Chase, as Syndication Agent, CL, as Co-Documentation
Agent, Scotiabank, as Co-Documentation Agent and Banc One Capital Markets, Inc.,
as Joint Lead Arranger and Bookrunner and JPMorgan Securities, Inc., as Joint
Lead Arranger and Bookrunner.

                                   WITNESSETH:

         WHEREAS, Borrower and certain of the Lenders ("Original Lenders") and
Agents entered into a Restated Credit Agreement dated as of May 3, 2002 (as
amended, restated and renewed from time to time, the "Credit Agreement")
pursuant to which Lenders agreed to make a revolving loan to the Borrower in
amounts of up to $275,000,000; and

         WHEREAS, Borrower, Lenders and Agents have agreed to amend the Credit
Agreement to make certain changes thereto as set forth herein and Comerica and
Natexis have agreed to purchase interests in the Loans concurrently with the
closing of this First Amendment.

         NOW, THEREFORE, the parties agree to amend the Credit Agreement as
follows:

         1.       Unless otherwise defined herein all defined terms used herein
shall have the same meaning as ascribed to such terms in the Credit Agreement.

         2.       Section 1 of the Credit Agreement is hereby amended in the
following respects:

                  (a)      By deleting the definition of "Consolidated Net
         Income" therefrom in its entirety and substituting the following in
         lieu thereof:

                  "Consolidated Net Income shall mean Borrower's consolidated
                  net income after income taxes calculated in accordance with
                  GAAP, but excluding any non-cash gains or losses as a result
                  of the application of FASB Statements 133 and 143."

<PAGE>

                  (b)      By deleting the definition of "Maturity Date"
         therefrom in its entirety and substituting the following in lieu
         thereof:

                  "Maturity Date shall mean January 1, 2007."

                  (c)      By deleting the definition of "Pre-Approved
         Contracts" therefrom in its entirety and substituting the following in
         lieu thereof:

                  "Pre-Approved Contracts as used herein shall mean any
                  contracts or agreements entered into in connection with any
                  Rate Management Transaction designed (i) to hedge, forward,
                  sell or swap crude oil or natural gas or otherwise sell up to
                  (A) 90% of the Borrower's anticipated production from proved,
                  developed producing reserves of crude oil, and/or 90% of the
                  Borrower's anticipated production from proved, developed
                  producing reserves of natural gas if all such contracts or
                  agreements have maturities of thirty-six (36) months or less,
                  and (B) 80% of the Borrower's anticipated production from
                  proved, developed producing reserves of crude oil, and/or 80%
                  of Borrower's anticipated production from proved, developed
                  producing reserves of natural gas if any of such contracts or
                  agreements has a maturity in excess of thirty-six (36) months,
                  and (ii) with one or more of the Lenders or counterparties to
                  the hedging agreement listed on Exhibit "F" hereto."

         3.       Section 12 of the credit Agreement is hereby amended by
deleting Subsection (a)(ii) therefrom in is entirety and substituting the
following in lieu thereof:

                  "(ii)    Quarterly Financing Statements. As soon as available,
                  and in any event within forty-five (45) days after the end of
                  each fiscal quarter of each year beginning with the fiscal
                  quarter ended March 31, 2003, the quarterly unaudited
                  consolidated Financial Statements of Borrower prepared in
                  accordance with GAAP; or"

         4.       Any and all references in the Credit Agreement to "Oceana
Exploration Company, L.C." are hereby amended to substitute the name "Victory
Energy Partners, L.L.C." in lieu thereof.

         5.       Exhibit "F" to the Credit Agreement is hereby amended by
adding the name "Mitsui & Co. Energy Risk Management, LTD." thereto.

         6.       As of April 1, 2003, the Borrowing Base shall be $225,000,000
until redetermined pursuant to Section 7(b) of the Credit Agreement.

         7.       The Lenders have agreed to reallocate their respective
Commitments and allow Comerica and Natexis to acquire an interest in the
Commitments and Loans. As required by the Credit Agreement, the Agent and the
Borrower, hereby consent to the sale of the portion of the

                                      -2-

<PAGE>

Commitments to Comerica and Natexis. After such reallocation of Commitments, the
Lenders shall own the Commitment Percentages set forth on Schedule 1 hereto as
of the First Amendment Effective Date. Each Lender shall surrender it's existing
Note and be issued a new Note on the face amount equal to each Lenders'
Commitment Percentage times $275,000,000. Each said Note to be in the form of
Exhibit B to the Credit Agreement with appropriate insertions thereto.

         8.       In consideration of the Lenders' agreement to extend the
Maturity Date, the Borrower hereby agrees to pay to the Lenders on the First
Amendment Effective Date an amount equal to $512,500, to be prorated among the
Original Lenders based upon their Commitment Percentages prior to the First
Amendment Effective Date. In addition and in consideration of the Lenders'
agreement to increase the Borrowing Base to $225,000,000, Borrower agrees to
pay, on the First Amendment Effective Date, a borrowing base increase fee to the
Lenders equal to $53,968.75 to be prorated among Lenders with new or increased
Commitments as of the First Amendment Effective Date.

         9.       Except to the extent its provisions are specifically amended,
modified or superseded by this First Amendment, the representations, warranties
and affirmative and negative covenants of the Borrower contained in the Credit
Agreement are incorporated herein by reference for all purposes as if copied
herein in full. The Borrower hereby restates and reaffirms each and every term
and provision of the Credit Agreement, as amended, including, without
limitation, all representations, warranties and affirmative and negative
covenants. Except to the extent its provisions are specifically amended,
modified or superseded by this First Amendment, the Credit Agreement, as
amended, and all terms and provisions thereof shall remain in full force and
effect, and the same in all respects are confirmed and approved by the Borrower
and the Lenders.

         10.      This First Amendment shall be effective as of the date first
above written, but only upon the satisfaction of the conditions precedent set
forth in Paragraphs 8 and 11 hereof (the "First Amendment Effective Date").

         11.      The obligations of Lenders under this First Amendment shall be
subject to the following conditions precedent:

                  (a)      Execution and Delivery. The Borrower and each
         Guarantor shall have executed and delivered this First Amendment, and
         other required documents, all in form and substance satisfactory to the
         Agent;

                  (b)      Representations and Warranties. The representations
         and warranties of the Borrowers under this First Amendment are true and
         correct in all material respects as of such date, as if then made
         (except to the extent that such representations and warranties related
         solely to an earlier date);

                  (c)      No Event of Default. No Event of Default shall have
         occurred and be continuing nor shall any event have occurred or failed
         to occur which, with the passage of time or service of notice, or both,
         would constitute an Event of Default;

                                      -3-

<PAGE>

                  (d)      Other Documents. The Agent shall have received such
         other instruments and documents incidental and appropriate to the
         transaction provided for herein as the Agent or its counsel may
         reasonably request, and all such documents shall be in form and
         substance satisfactory to the Agent;

                  (e)      Legal Matters Satisfactory. All legal matters
         incident to the consummation of the transactions contemplated hereby
         shall be reasonably satisfactory to special counsel for the Agent
         retained at the expense of Borrower.

         12.      Borrower hereby represents and warrants that all factual
information heretofore and contemporaneously furnished by or on behalf of
Borrower to Agent for purposes of or in connection with this First Amendment
does not contain any untrue statement of a material fact or omit to state any
material fact necessary to keep the statements contained herein or therein from
being misleading. Each of the foregoing representations and warranties shall
constitute a representation and warranty of Borrower made under the Credit
Agreement, and it shall be an Event of Default if any such representation and
warranty shall prove to have been incorrect or false in any material respect at
the time given. Each of the representations and warranties made under the Credit
Agreement (including those made herein) shall survive and not be waived by the
execution and delivery of this First Amendment or any investigation by Lenders.

         13.      The Borrower agrees to indemnify and hold harmless the Lenders
and their respective officers, employees, agents, attorneys and representatives
(singularly, an "Indemnified Party", and collectively, the "Indemnified
Parties") from and against any loss, cost, liability, damage or expense
(including the reasonable fees and out-of-pocket expenses of counsel to the
Lender, including all local counsel hired by such counsel) ("Claim") incurred by
the Lenders in investigating or preparing for, defending against, or providing
evidence, producing documents or taking any other action in respect of any
commenced or threatened litigation, administrative proceeding or investigation
under any federal securities law, federal or state environmental law, or any
other statute of any jurisdiction, or any regulation, or at common law or
otherwise, which is alleged to arise out of or is based upon any acts, practices
or omissions or alleged acts, practices or omissions of the Borrower or its
agents or arises in connection with the duties, obligations or performance of
the Indemnified Parties in negotiating, preparing, executing, accepting,
keeping, completing, countersigning, issuing, selling, delivering, releasing,
assigning, handling, certifying, processing or receiving or taking any other
action with respect to the Loan Documents and all documents, items and materials
contemplated thereby even if any of the foregoing arises out of an Indemnified
Party's ordinary negligence. The indemnity set forth herein shall be in addition
to any other obligations or liabilities of the Borrower to the Lenders hereunder
or at common law or otherwise, and shall survive any termination of this First
Amendment, the expiration of the Loan and the payment of all indebtedness of the
Borrower to the Lenders hereunder and under the Notes, provided that the
Borrower shall have no obligation under this section to the Lenders with respect
to any of the foregoing arising out of the gross negligence or willful
misconduct of the Lenders. If any Claim is asserted against any Indemnified
Party, the Indemnified Party shall endeavor to notify the Borrower of such Claim
(but failure to do so shall not affect the indemnification herein made except to
the extent of the actual harm caused by such failure). The Indemnified Party
shall have the right to employ, at the

                                      -4-

<PAGE>

Borrower's expense, counsel of the Indemnified Parties' choosing and to control
the defense of the Claim. The Borrower may at its own expense also participate
in the defense of any Claim. Each Indemnified Party may employ separate counsel
in connection with any Claim to the extent such Indemnified Party believes it
reasonably prudent to protect such Indemnified Party. THE PARTIES INTEND FOR THE
PROVISIONS OF THIS SECTION TO APPLY TO AND PROTECT EACH INDEMNIFIED PARTY FROM
THE CONSEQUENCES OF STRICT LIABILITY IMPOSED OR THREATENED TO BE IMPOSED ON ANY
INDEMNIFIED PARTY AS WELL AS FROM THE CONSEQUENCES OF ITS OWN NEGLIGENCE,
WHETHER OR NOT THAT NEGLIGENCE IS THE SOLE, CONTRIBUTING, OR CONCURRING CAUSE OF
ANY CLAIM.

         14.      This First Amendment may be executed in any number of
counterparts and all of such counterparts taken together shall be deemed to
constitute one and the same instrument.

         15.      WRITTEN CREDIT AGREEMENT. THE CREDIT AGREEMENT, AS AMENDED BY
THE FIRST AMENDMENT AND THIS FIRST AMENDMENT REPRESENTS THE FINAL AGREEMENT
BETWEEN AND 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 BETWEEN AND AMONG THE PARTIES.

         16.      The Guarantors hereby consent to the execution of this First
Amendment by the Borrower and reaffirms their guaranties of all of the
obligations of the Borrower to the Lenders. Borrower and Guarantors acknowledge
and agree that the renewal, extension and amendment of the Credit Agreement
shall not be considered a novation of account or new contract but that all
existing rights, titles, powers, and estates in favor of the Lenders constitute
valid and existing obligations in favor of the Lenders. Borrower and Guarantors
each confirm and agree that (a) neither the execution of this First Amendment or
any other Loan Document nor the consummation of the transactions described
herein and therein shall in any way effect, impair or limit the covenants,
liabilities, obligations and duties of the Borrower and the Guarantors under the
Loan Documents and (b) the obligations evidenced and secured by the Loan
Documents continue in full force and effect. Each Guarantor hereby further
confirms that it unconditionally guarantees to the extent set forth in their
respective Guaranties the due and punctual payment and performance of any and
all amounts and obligations owed to the Lenders under the Credit Agreement or
the other Loan Documents.

                                      -5-

<PAGE>

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

                                       BORROWER:

                                       GREAT LAKES ENERGY PARTNERS, L.L.C.,
                                       a Delaware limited liability company

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                       GUARANTORS:

                                       VICTORY ENERGY PARTNERS, L.L.C.

                                       By:  Great Lakes Energy Partners, L.L.C.,
                                            managing member

                                            By: ________________________________
                                            Name: ______________________________
                                            Title: _____________________________

                                       OHIO INTRASTATE GAS TRANSMISSION
                                       COMPANY

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -6-

<PAGE>

                                       LENDERS AND AGENTS:

                                       BANK ONE, NA
                                       as a Lender and as Administrative Agent
                                       (Main Office Chicago)

                                       By: ____________________________________
                                               Wm. Mark Cranmer, Director,
                                               Capital Markets

                                      -7-

<PAGE>

                                       JPMORGAN CHASE BANK
                                       as a Lender and as Syndication Agent

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -8-

<PAGE>

                                       CREDIT LYONNAIS NEW YORK BRANCH
                                       as a Lender and as Co-Documentation Agent

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -9-

<PAGE>

                                       BANK OF SCOTLAND

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -10-

<PAGE>

                                       THE BANK OF NOVA SCOTIA
                                       as a Lender and as Co-Documentation Agent

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -11-

<PAGE>

                                       FORTIS CAPITAL CORP.

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -12-

<PAGE>

                                       THE FROST NATIONAL BANK

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -13-

<PAGE>

                                       UNION BANK OF CALIFORNIA, N.A.

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -14-

<PAGE>

                                       COMERICA BANK-TEXAS

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -15-

<PAGE>

                                       NATEXIS BANQUES POPULAIRES

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                       By: _____________________________________
                                       Name: ___________________________________
                                       Title: __________________________________

                                      -16-

<PAGE>

                                   SCHEDULE 1

                      New $225MM BB/ $275MM (*) Allocation

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------
                                BB Commitment       %                                               Face Note
----------------------------------------------------------------------------------------------------------------
<S>                            <C>                <C>              <C>                            <C>
Bank One                       $34,337,500.00     15.26%           15.261111111111100%            $41,968,055.56
----------------------------------------------------------------------------------------------------------------
Credit Lyonnais                $34,337,500.00     15.26%           15.261111111111100%            $41,968,055.56
----------------------------------------------------------------------------------------------------------------
Bank of Scotland               $33,825,000.00     15.03%           15.033333333333300%            $41,341,666.67
----------------------------------------------------------------------------------------------------------------
Bank of Nova Scotia            $30,955,000.00     13.76%           13.757777777777800%            $37,833,888.89
----------------------------------------------------------------------------------------------------------------
Fortis Capital                 $26,957,500.00     11.98%           11.981111111111100%            $32,948,055.56
----------------------------------------------------------------------------------------------------------------
JP Morgan Chase                $22,500,000.00     10.00%           10.000000000000000%            $27,500,000.00
----------------------------------------------------------------------------------------------------------------
Frost National Bank            $11,837,500.00      5.26%            5.261111111111110%            $14,468,055.56
----------------------------------------------------------------------------------------------------------------
Union Bank of California       $10,250,000.00      4.56%            4.555555555555560%            $12,527,777.78
----------------------------------------------------------------------------------------------------------------
Comerica                       $10,000,000.00      4.44%            4.444444444444440%            $12,222,222.22
----------------------------------------------------------------------------------------------------------------
Natexis                        $10,000,000.00      4.44%            4.444444444444440%            $12,222,222.22
----------------------------------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------
                              $225,000,000.00    100.00%                       100.00%           $275,000,000.00
----------------------------------------------------------------------------------------------------------------
</TABLE>