EXHIBIT NUMBER 10.51



                  SEVENTH AMENDMENT TO SECURED CREDIT AGREEMENT
                  ---------------------------------------------

                  This Seventh Amendment to Secured Credit Agreement (this
"AGREEMENT") is dated as of November 19, 1999 by and among Gibraltar Packaging
Group, Inc., a Delaware corporation (the "BORROWER"), the financial institutions
parties to the Credit Agreement (as defined herein) (collectively, the "LENDERS"
and individually, a "LENDER") and First Source Financial LLP, as Agent for the
Lenders (the "AGENT").


                                    RECITALS
                                    --------

                  WHEREAS, the Borrower, the Agent and the Lenders are parties
to that certain Secured Credit Agreement, dated as of July 31, 1998 (the
"ORIGINAL CREDIT AGREEMENT"), as amended by that certain First Amendment to
Secured Credit Agreement, dated as of September 1, 1998 (the "FIRST AMENDMENT"),
that certain Second Amendment to Secured Credit Agreement, dated as of November
13, 1998 (the "SECOND AMENDMENT"), that certain Third Amendment to Secured
Credit Agreement, dated as of February 12, 1999 (the "THIRD AMENDMENT"), that
certain Fourth Amendment to Secured Credit Agreement, dated as of May 14, 1999
(the "FOURTH AMENDMENT"), that certain Fifth Amendment to Secured Credit
Agreement, dated as of September 29, 1999 (the "FIFTH AMENDMENT") and that
certain Sixth Amendment to Secured Credit Agreement, dated as of October 26,
1999 (the "SIXTH AMENDMENT"); the Original Credit Agreement, as amended by the
First Amendment, the Second Amendment, the Third Amendment, the Fourth
Amendment, the Fifth Amendment and the Sixth Amendment, is collectively referred
to herein as the "SECURED CREDIT AGREEMENT"), among the Borrower, the Agent and
the Lenders;

                  WHEREAS, the Borrower wishes, and the Agent and the Lenders
are willing, to amend certain provisions of the Secured Credit Agreement and to
waive compliance with certain provisions of the Secured Credit Agreement, all on
the terms and conditions set forth in this Agreement.

                  WHEREAS, First Source Financial LLP and LaSalle Business
Credit, Inc. are the only Lenders which are parties to the Secured Credit
Agreement as of the date hereof; and

                  NOW, THEREFORE, in consideration of the mutual agreements
contained herein, the parties hereto agree as follows:
<PAGE>
                                    AGREEMENT
                                    ---------

1.       Definitions. Capitalized terms used but not otherwise defined herein
shall have the meanings as set forth in the Secured Credit Agreement.

2.       Amendments to Secured Credit Agreement. Section 11.32 of the Secured
Credit Agreement is hereby amended as follows:

         (a)   Section 11.32(a) of the Secured Credit Agreement is hereby
               amended by deleting the phrase "December 31, 1999 through July 2,
               2000" appearing therein and the corresponding minimum Net Worth
               requirement therefor and replacing it with the following:

                                                                   MINIMUM
                      PERIODS (ALL DATES ARE INCLUSIVE)            NET WORTH
                  October 1, 1999 through December 31, 1999       $   700,000
                  January 1, 2000 through March 31, 2000          $   900,000
                  April 1, 2000 through July 1, 2000              $ 1,100,000

         (b)   Sections 11.32(b), (c) and (d) of the Secured Credit Agreement
               are hereby amended by deleting them in their entirety and
               replacing them with the following:

                           (b) Debt to EBITDA Ratio. Not permit the Debt to
         EBITDA Ratio for any period set forth below to be more than the ratio
         listed below opposite such period:
<TABLE>
<CAPTION>
<S>                                                                                  <C>
                                                                                    MAXIMUM
                           PERIOD(S) (ALL DATES ARE INCLUSIVE)                       RATIO
                  Fiscal Quarter ending September 30, 1999                         7.00:1.0
                  Fiscal Quarter ending December 31, 1999                          6.00:1.0
                  Fiscal Quarter ending March 31, 2000                             4.75:1.0
                  Fiscal Quarter ending July 1, 2000                               4.00:1.0
                  Each Fiscal Quarter of Fiscal Year 2001                          3.00:1.0
                  Each Fiscal Quarter of Fiscal Year 2002                          2.50:1.0
                  Fiscal Quarter ending on June 30, 2002 and each Fiscal           2.50:1.0
                  Quarter thereafter

                           (c) Interest Coverage Ratio. Not permit the Interest
         Coverage Ratio measured on the last day of any month for any twelve
         (12) month period (or, in the case of months ending before July 1,
         2000, for the period from and including July 4, 1999, to and including
         the last day of such month) ending on the last day of such month to be
         less than the ratio listed below opposite the period including such
         month:

<CAPTION>
<S>                                                                                  <C>
                                                                                    MINIMUM
                           PERIOD(S) (ALL DATES ARE INCLUSIVE)                       RATIO
</TABLE>
                                      -2-
<PAGE>
<TABLE>
<CAPTION>
<S>                                                                                  <C>
                                                                                    MINIMUM
                           PERIOD(S) (ALL DATES ARE INCLUSIVE)                       RATIO
                  Fiscal Quarter ending September 30, 1999                         1.50:1.0
                  Fiscal Quarter ending December 31, 1999                          2.00:1.0
                  Fiscal Quarters ending March 31, 2000 and July 1, 2000           2.10:1.0
                  July 2, 2000 and thereafter                                      2.50:1.0

                           (d) Fixed Charge Coverage Ratio. Not permit the Fixed
         Charge Coverage Ratio measured on the last day of any month for any
         twelve (12) month period (or, in the case of months ending before July
         1, 2000, for the period from and including July 4, 1999, to and
         including the last day of each month) ending on the last day of such
         month to be less than the ratio listed below opposite the period
         including such month:
<CAPTION>
<S>                                                                                   <C>
                                                                                    MINIMUM
                           PERIOD(S) (ALL DATES ARE INCLUSIVE)                       RATIO
                  September 30, 1999 through July 1, 2000                          1.00:1.0
                  July 2, 2000 through June 30, 2001                               1.10:1.0
                  July 1, 2001 through June 29, 2002                               1.10:1.0
                  June 30, 2002 and thereafter                                     1.10:1.0
</TABLE>
     3.  Representations and Warranties. To induce the Agent and the Lenders to
enter into this Agreement and to make all future Loans under the Secured Credit
Agreement, the Borrower represents and warrants to the Agent and the Lenders
that:

         (a) Due Authorization, etc. The execution, delivery and performance by
     the Borrower of this Agreement executed as of the date hereof are within
     its corporate powers, have been duly authorized by all necessary corporate
     action (including without limitation, shareholder approval, if any shall be
     required), have received all necessary governmental approval (if any shall
     be required), and do not and will not contravene or conflict with any
     Requirement of Law or Contractual Obligation binding upon such entity. This
     Agreement is the legal, valid, and binding obligation of the Borrower
     enforceable against the Borrower in accordance with its respective terms.

         (b) Certain Agreements. To the best of the Borrower's knowledge, on the
     date hereof all warranties of the Borrower thereto set forth in the Secured
     Credit Agreement, as amended hereby, are true and correct in all material
     respects, without any waiver or modification thereof and no default of any
     party exists under the Secured Credit Agreement or any Related Document.

         (c) Financial Information. All balance sheets, all statement of
     operations, of shareholders' equity and of changes in financial position,
     and other financial data which have been or shall hereafter be furnished to
     the Agent for the purposes of or in connection with this Agreement have
     been and will be prepared in accordance with GAAP consistently applied
     throughout the periods involved and do and will, present fairly the

                                      -3-
<PAGE>
     financial condition of the entities involved as of the dates thereof and
     the results of their operations for the periods covered thereby.

         (d) Litigation. No material litigation (including, without limitation,
     derivative actions), arbitrations, governmental investigation or proceeding
     or inquiry shall, on the date hereof, be pending which was not previously
     disclosed in writing to the Agent and no material adverse development shall
     have occurred in any litigation (including, without limitation, derivative
     actions), arbitration, government investigations, or proceeding or inquiry
     previously disclosed to the Agent in writing.

     4.  Conditions to Effectiveness. This Agreement shall be effective as of
November___, 1999 upon the satisfaction of the conditions set forth in this
Section 4 and delivery of the following documents to the Agent on or prior to
the date hereof (unless another date is specified), in form and substance
satisfactory to the Agent and the Lenders:

         (a) Agreement. The Borrower shall have delivered to the Agent executed
     originals of this Agreement.

         (b) Consents and Acknowledgments. The Borrower shall have obtained all
     consents, approvals and acknowledgments which may be required with respect
     to the execution, delivery and performance of this Agreement.

         (c) No Default. As of the date hereof after giving effect to this
     Agreement, no Unmatured Event of Default or Event of Default under any
     Related Document shall have occurred and be continuing.

     5. Affirmation of Guaranties.

         Each Guarantor (i) consents to and approves the execution and delivery
of this Agreement by the Borrower, the Agent and the Lenders, (ii) agrees that
this Agreement does not and shall not limit or diminish in any manner its
obligations under its Guaranty or under any of the other Related Documents to
which it is a party, (iii) agrees that this Agreement shall not be construed as
requiring the consent of any Guarantor in any other circumstance, (iv) reaffirms
its obligations under its Guaranty and all of the other Related Documents to
which it is a party, and (v) agrees that its Guaranty and such other Related
Documents remain in full force and effect and are each hereby ratified and
confirmed.

     6. Miscellaneous.

         (a) Captions. Section captions used in this Agreement are for
     convenience only, and shall not affect the construction of this Agreement.

         (b) Governing Law. This Agreement shall be a contract made under and
     governed by the laws of the State of Illinois, without regard to conflict
     of laws principles. Wherever possible each provision of this Agreement
     shall be interpreted in such manner to be effective and valid under
     applicable law, but if any provision of this Agreement shall be prohibited
     by or invalid under such law, such provision shall be ineffective to the

                                      -4-
<PAGE>
     extent of such prohibition or invalidity, without invalidating the
     remainder of such provisions or the remaining provision of this Agreement.

         (c) Counterparts. This Agreement may be executed in any number of
     counterparts and by the different parties on separate counterparts, and
     each such counterpart shall be deemed to be an original, but all such
     counterparts shall together constitute one and the same Agreement. Delivery
     of an executed counterpart of a signature page to this Agreement by
     telecopy shall be effective as delivery of a manually executed counterpart
     of this Agreement.

         (d) Successors and Assignees. This Agreement shall be binding upon the
     Borrower, the Agent, the Lenders and their respective successors and
     assignees, and shall inure to the sole benefit of the Borrower, the Agent,
     the Lenders and their successors and assignees.

         (e) References. Any reference to the Secured Credit Agreement contained
     in any notice, request, certificate, or other document executed
     concurrently with or after the execution and delivery of this Agreement
     shall be deemed to include this Agreement unless the context shall
     otherwise require.

         (f) Continued Effectiveness. Notwithstanding anything contained herein,
     the terms of this Agreement are not intended to and do not serve to effect
     a novation as to the Secured Credit Agreement, any Note or any of the
     Collateral Documents provided to furnish security therefor. The parties
     hereto expressly do not intend to extinguish the Secured Credit Agreement,
     any Note or the Collateral Documents. Instead, it is the express intention
     of the parties hereto to reaffirm the existence of the indebtedness created
     under the Secured Credit Agreement which is evidenced by Notes and secured
     by the various Collateral Documents. The Secured Credit Agreement and each
     of the Related Documents as amended hereby remain in full force and effect.
     The execution, delivery and effectiveness of this Agreement shall not
     operate as a waiver of any right, power or remedy of the Lenders or the
     Agent under the Secured Credit Agreement or any Related Document to which
     the Lenders and the Agent are a party nor constitute a waiver of any
     provision in or Event of Default or Unmatured Event of Default (now or
     hereafter existing) under the terms of the Secured Credit Agreement or any
     Related Document.

         (g) Fees and Expenses. In accordance with Section 14.4 of the Secured
     Credit Agreement, the Borrower agrees to pay on demand all fees, costs and
     expenses incurred by the Agent and the Lenders in connection with the
     preparation, execution and delivery of this Agreement.

                                    * * * * *

                                      -5-
<PAGE>


                  IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be executed by their respective officers thereunto duly authorized,
as of the date first above written.

                                    GIBRALTAR PACKAGING GROUP, INC., as
                                    Borrower


                                    By: /s/ John W. Lloyd
                                    Name Printed: John W. Lloyd
                                    Title: Executive Vice President


                                    FIRST SOURCE FINANCIAL LLP,
                                          as Agent and a Lender

                                    By:   First Source Financial, Inc.
                                    Its:  Manager


                                    By: /s/ Kathi J. Inorio
                                    Name Printed: Kathi J. Inorio
                                    Title: Vice President


                                    LASALLE BUSINESS CREDIT, INC.,
                                          as a Lender


                                    By: /s/ Ellen T. Cook
                                    Name Printed: Ellen T. Cook
                                    Title: Vice President


                                    RIDGEPAK CORPORATION, as a Guarantor


                                    By: /s/ John W. Lloyd
                                    Name Printed: John W. Lloyd
                                    Title: Secretary


                                    NIEMAND HOLDINGS, INC., as a Guarantor


                                    By: /s/ John W. Lloyd
                                    Name Printed: John W. Lloyd
                                    Title: Secretary

                                      S-1
                              [TO SEVENTH AMENDMENT]
<PAGE>
                                     NIEMAND INDUSTRIES, INC., as a Guarantor


                                     By: /s/ John W. Lloyd
                                     Name Printed: John W. Lloyd
                                     Title: Secretary

                                     BURLINGTON HOLDINGS, INC. (f/k/a GB
                                     Labels, Inc.), as a  Guarantor


                                     By: /s/ John W. Lloyd
                                     Name Printed: John W. Lloyd
                                     Title: Secretary


                                     STANDARD PACKAGING AND PRINTING
                                     CORP., as a Guarantor


                                     By: /s/ John W. Lloyd
                                     Name Printed: John W. Lloyd
                                     Title: Secretary

                                      S-2
                              [TO SEVENTH AMENDMENT]