<PAGE>
                                                                   Exhibit 10.49


            SIXTH AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT

         This Sixth Amendment to Amended and Restated Credit Agreement (herein,
the "Amendment") is made as of March 15, 2004, by and among Morton Industrial
Group, Inc., a Georgia corporation (the "Borrower"), the Lenders party to the
Credit Agreement hereinafter identified and defined, and Harris Trust and
Savings Bank, as Agent for the Lenders (in such capacity, the "Agent").

                                    RECITALS

         A. The Lenders currently extend credit to the Borrower on the terms and
conditions set forth in that certain Amended and Restated Credit Agreement dated
as of February 25, 2002, as amended, by and among the Borrower, the Guarantors,
the Lenders, and the Agent (the "Credit Agreement"). All capitalized terms used
herein without definition shall have the same meanings herein as such terms have
in the Credit Agreement.

         B. The Borrower has requested that the Lenders increase the Capital
Expenditure limit for fiscal 2003 and make certain changes to the Borrowing
Base, and the Lenders are willing to agree to such changes, all on the terms and
conditions herein set forth.

         NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

SECTION 1.            AMENDMENTS.

         Subject to the satisfaction of the conditions set forth in Section 3
below, the Credit Agreement shall be and hereby is amended as follows:

        1.1. The definition of "Borrowing Base" set forth in Section 5.1 of the
Credit Agreement is hereby amended and restated to read in its entirety as
follows:

               "Borrowing Base" means, as of any time it is to be
determined, the sum of:


                 (a) 85% of the then net book value of Eligible Accounts
(computed using the method of receivables valuation applied by the Borrower in
accordance with GAAP which reflects such value as the net book value of its
receivables, except that net book value for such purposes shall not reflect any
reserve for accounts more than ninety days past due that have already been
excluded from gross accounts in computing such Eligible Accounts) less such
other reserves for uncollectibility, location of account debtor, contras and
other matters as the Agent or Required Lenders in good

<PAGE>
faith shall from time to time reasonably deem appropriate to adjust such net
book value; plus

                 (b) 60% of the value (computed at its cost using the method of
inventory valuation applied by the Borrower in accordance with GAAP which
reflects such cost on the Borrower's books as its net book value, but in any
event after reducing such value as so computed by the aggregate amount of all
reserves for obsolescence, slow-moving items, shrinkage and all such other
matters as the Agent or Required Lenders in good faith shall from time to time
reasonably deem appropriate to adjust such net book value) of Eligible
Inventory; plus

                 (c) the Other Asset Value then in effect;

provided that the Borrowing Base shall be computed only as against and on so
much of the Collateral as is included on the certificates to be furnished from
time to time by the Borrower pursuant to Section 8.5(f) hereof and, if required
by the Agent pursuant to any of the terms hereof or any Collateral Document, as
verified by such other evidence required to be furnished to the Agent pursuant
hereto or pursuant to any such Collateral Document. Notwithstanding the
foregoing to the contrary: (i)the amount of Eligible Accounts otherwise included
in the Borrowing Base shall be reduced, dollar for dollar, by a reserve equal to
the greater of (a) the amount (if any) by which (x) the aggregate amount of
accounts payable owing by the Borrower and its Subsidiaries to Deere and
Caterpillar together and their respective Affiliates for inventory and supplies
purchased (the "Deere/Caterpillar Payables") at any time exceeds (y) $5,000,000
or (b) the sum of (A) the amount (if any) by which (x) the aggregate amount of
accounts payable owing by the Borrower and its Subsidiaries to Deere and its
Affiliates for inventory and supplies purchased (the "Deere Payables") at any
time exceeds (y) $3,000,000 and (B) the amount (if any) by which (x) the
aggregate amount of accounts payable owing by the Borrower and its Subsidiaries
to Caterpillar and its Affiliates for inventory and supplies purchased (the
"Caterpillar Payables") at any time exceeds (y) $3,000,000; (ii) no reserve will
be imposed in computing the Borrowing


                                      -2-
<PAGE>



Base as of any time solely in respect of the Deere/Caterpillar Payables, Deere
Payables or Caterpillar Payables to the extent the same do not exceed such
respective limits; and (iii) the Agent and the Required Lenders shall have the
right to impose reserves for other matters arising in connection with
receivables owing by Deere and Caterpillar and to otherwise impose reserves in
accordance with the Credit Agreement.

        1.2 Section 8.10 of the Credit Agreement is hereby amended and restated
to read in its entirety as follows:

Section 8.10. Capital Expenditures. The Borrower will not, nor will it permit
any Subsidiary to, expend or (without duplication) become obligated to expend,
in each case for Capital Expenditures aggregating for the Borrower and its
Subsidiaries (taken together) in excess of (i) $3,900,000 during fiscal 2003,
(ii) $4,500,000 during fiscal 2004 and (iii) $1,250,000 during the period from
January 1, 2005 through and including the Termination Date.

SECTION 2.            CONDITIONS PRECEDENT.

         The effectiveness of this Amendment is subject to the satisfaction of
all of the following conditions precedent:

        2.1. The Borrower, the Agent, and the Lenders shall have executed and
delivered this Amendment, and the Guarantors shall have executed and delivered
their consent to this Amendment in the space provided for that purpose below.

        2.2. Legal matters incident to this Amendment shall be satisfactory to
the Agent and the Lenders and their counsel.

        2.3. The Borrower shall have paid all fees and expenses of counsel to
the Agent with respect to the preparation of this Amendment as well as all prior
fees and charges of counsel to the Agent incurred prior to the date hereof which
remain outstanding and unpaid.

SECTION 3.            REPRESENTATIONS.

         In order to induce the Lenders to execute and deliver this Amendment,
the Borrower hereby represents to the Lenders that as of the date hereof, and
after giving effect to this Amendment, (a) the representations and warranties
set forth in Section 6 of the Credit Agreement are and shall be and remain true
and correct in all material respects (except that for purposes of this paragraph
the representations contained in Section 6.4 shall be deemed to refer to the
most recent financial statements of the Borrower delivered to the Lenders) and
(b) the Borrower is in full compliance with all of the terms and conditions of
the Credit Agreement after


                                      -3-
<PAGE>

giving effect to this Amendment and no Default or Event of Default has occurred
and is continuing under the Credit Agreement or shall result after giving effect
to this Amendment.

SECTION 4.           RELEASE OF CLAIMS.

         TO INDUCE THE LENDERS AND THE AGENT TO ENTER INTO THIS AMENDMENT, THE
BORROWER AND THE GUARANTORS HEREBY RELEASE, ACQUIT, AND FOREVER DISCHARGE THE
LENDERS, THE AGENT AND THEIR AFFILIATES AND THEIR RESPECTIVE OFFICERS,
DIRECTORS, AGENTS, ATTORNEYS, ADVISORS, CONSULTANTS, EMPLOYEES, SUCCESSORS AND
ASSIGNS, FROM ALL LIABILITIES, CLAIMS, DEMANDS, ACTIONS, AND CAUSES OF ACTION OF
ANY KIND (IF THERE ARE ANY), WHETHER ABSOLUTE OR CONTINGENT, DUE OR TO BECOME
DUE, DISPUTED OR UNDISPUTED, AT LAW OR IN EQUITY, THAT THEY NOW HAVE OR EVER HAD
AGAINST THE LENDERS, THE AGENT AND THE OTHER PARTIES IDENTIFIED ABOVE, OR ANY
ONE OR MORE OF THEM INDIVIDUALLY, UNDER OR IN CONNECTION WITH THE CREDIT
AGREEMENT OR ANY OF THE OTHER LOAN DOCUMENTS.

SECTION 5.            MISCELLANEOUS.

        5.1. The Borrower has heretofore executed and delivered to the Agent and
the Lenders certain of the Collateral Documents. The Borrower hereby
acknowledges and agrees that, notwithstanding the execution and delivery of this
Amendment, the Collateral Documents remain in full force and effect and the
rights and remedies of the Agent and the Lenders thereunder, the obligations of
the Borrower thereunder, and the liens and security interests created and
provided for thereunder remain in full force and effect and shall not be
affected, impaired, or discharged hereby. Nothing herein contained shall in any
manner affect or impair the priority of the liens and security interests created
and provided for by the Collateral Documents as to the indebtedness which would
be secured thereby prior to giving effect to this Amendment.

        5.2. Except as specifically amended herein or waived hereby, the Credit
Agreement shall continue in full force and effect in accordance with its
original terms. Reference to this specific Amendment need not be made in the
Credit Agreement, the Notes, or any other instrument or document executed in
connection therewith, or in any certificate, letter or communication issued or
made pursuant to or with respect to the Credit Agreement, any reference in any
of such items to the Credit Agreement being sufficient to refer to the Credit
Agreement as amended hereby.

        5.3. The Borrower agrees to pay all reasonable out-of-pocket costs and
expenses incurred by the Agent and the Lenders in connection with the
preparation, execution and delivery of this Amendment and the documents and
transactions contemplated hereby, including the reasonable fees and expenses of
counsel for the Agent with respect to the foregoing.


                                      -4-
<PAGE>


        5.4. This Amendment may be executed in any number of counterparts, and
by the different parties on different counterpart signature pages, all of which
taken together shall constitute one and the same agreement. Any of the parties
hereto may execute this Amendment by signing any such counterpart and each of
such counterparts shall for all purposes be deemed to be an original. This
Amendment shall be governed by the internal laws of the State of Illinois.

                                      [SIGNATURE PAGES TO FOLLOW]






                                      -5-
<PAGE>

         This Sixth Amendment to Amended and Restated Credit Agreement is
entered into by the parties hereto as of the date and year first above written.

                                         MORTON INDUSTRIAL GROUP, INC.

                                         By  /s/ RODNEY B. HARRISON
                                            ------------------------------------
                                            Name  Rodney B. Harrison
                                                 -------------------------------
                                            Title  VP of Finance
                                                  ------------------------------

                                         Accepted and agreed to.

                                         HARRIS TRUST AND SAVINGS BANK

                                         By  /s/ LAWRENCE A. MIZERA
                                            ------------------------------------
                                            Name  Lawrence A. Mizera
                                                 -------------------------------
                                            Title  Vice President
                                                  ------------------------------

                                         BRANCH BANKING & TRUST CO.

                                         By  /s/ WORD C. CLARK, JR.
                                            ------------------------------------
                                            Name  Word C. Clark, Jr.
                                                 -------------------------------
                                            Title  SVP
                                                  ------------------------------

                                         U.S. BANK NATIONAL ASSOCIATION

                                            f/k/a Firstar Bank, N.A.

                                         By  /s/ RON SHAPIRO
                                            ------------------------------------
                                            Name  Ron Shapiro
                                                 -------------------------------
                                            Title  VP
                                                  ------------------------------

                                         LASALLE BANK NATIONAL ASSOCIATION

                                         By  /s/ JAMES D. THOMPSON
                                            ------------------------------------
                                            Name  James D. Thompson
                                                 -------------------------------
                                            Title  Group Senior VP
                                                  ------------------------------

                                         NATIONAL CITY BANK

                                         By  /s/ STEPHEN A. MONTO
                                            ------------------------------------
                                            Name  Stephen A. Monto
                                                 -------------------------------
                                            Title  Account Officer
                                                  ------------------------------


                                      -6-
<PAGE>

                    GUARANTORS' ACKNOWLEDGEMENT AND CONSENT

         Each of the undersigned hereby acknowledges and agrees that it is a
Guarantor under the terms of Section 11 of the Credit Agreement and, as such has
executed and delivered certain Collateral Documents pursuant to the Credit
Agreement. The undersigned hereby consent to the Sixth Amendment to Amended and
Restated Credit Agreement as set forth above and agree to the terms thereof,
including, without limitation, Section 5 thereof, and the undersigned hereby
confirm that their guaranties and the Collateral Documents executed by them, and
all of the obligations of the undersigned thereunder, remain in full force and
effect. The undersigned further agree that the consent of the undersigned to any
further amendments to the Credit Agreement shall not be required as a result of
this consent having been obtained. The undersigned acknowledge the Lenders are
relying on this acknowledgement and consent in entering into the Sixth Amendment
to Amended and Restated Credit Agreement with the Borrower.

                                         MORTON METALCRAFT CO.

                                         By  /s/ DARYL R. LINDEMANN
                                            ------------------------------------
                                            Name  Daryl R. Lindemann
                                                 -------------------------------
                                            Title  Vice President
                                                  ------------------------------

                                         MORTON METALCRAFT CO. OF NORTH CAROLINA

                                         By  /s/ DARYL R. LINDEMANN
                                            ------------------------------------
                                            Name  Daryl R. Lindemann
                                                 -------------------------------
                                            Title  Vice President
                                                  ------------------------------

                                         MORTON METALCRAFT CO. OF SOUTH CAROLINA

                                         By  /s/ DARYL R. LINDEMANN
                                            ------------------------------------
                                            Name  Daryl R. Lindemann
                                                 -------------------------------
                                            Title  Vice President
                                                  ------------------------------

                                         MID CENTRAL PLASTICS, INC.

                                         By  /s/ DARYL R. LINDEMANN
                                            ------------------------------------
                                            Name  Daryl R. Lindemann
                                                 -------------------------------
                                            Title  Vice President
                                                  ------------------------------

                                         B&W METAL FABRICATORS, INC.

                                         By  /s/ DARYL R. LINDEMANN
                                            ------------------------------------
                                            Name  Daryl R. Lindemann
                                                 -------------------------------
                                            Title  Vice President
                                                  ------------------------------