Document:

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                                                                EXHIBIT 10(a)(4)

                               AMENDMENT NO. 3 TO
                             SECURED PROMISSORY NOTE

         THIS AMENDMENT NO. 3 TO SECURED PROMISSORY NOTE (this "Amendment")
entered into as of this 20th day of April, 1999, by and between Navistar
International Transportation Corp., a Delaware corporation ("Navistar", and Core
Materials Corporation, a Delaware corporation (the "Company").

                                   WITNESSETH:

         WHEREAS, Navistar and RYMAC Mortgage Investment Corporation ("RYMAC")
entered into a certain Asset Purchase Agreement dated as of September 12, 1996,
as amended (the "Purchase Agreement"), pursuant to which the Company (as
successor to RYMAC) purchased those certain assets of Navistar's Columbus
Plastics Operation as described in the Purchase Agreement (the "Assets"),
subject to the terms and conditions therein;

         WHEREAS, unless otherwise defined herein, capitalized terms used herein
shall have the same meanings set forth in the Purchase Agreement;

         WHEREAS, as part of the consideration for the sale of the Assets, the
Company previously executed and delivered to Navistar that certain Secured
Promissory Note dated as of December 31, 1996, in the original principal amount
of Twenty Five Million Five Hundred Four Thousand and 00/100 Dollars
($25,504,000.00), subject to adjustment as provided therein (the "Note");

         WHEREAS, the Note was amended by an Amendment No. 1 to Secured
Promissory Note executed by the Company and Navistar dated as of December 31,
1996 (the "First Note Amendment"), and by and Amendment No. 2 to Secured
Promissory Note executed by the Company and Navistar dated as of April 6, 1998
(the "Second Note Amendment"; the Note, as amended by the First Note Amendment
and the Second Note Amendment, is hereinafter referred to as the "Amended
Note");

         WHEREAS, the current outstanding principal balance of the Amended Note
as of the date hereof, without giving effect to this Amendment, is Fifteen
Million Eight Hundred Twenty-One Thousand Eight Hundred Forty-One and 00/100
Dollars ($15,821,841.00);

         WHEREAS, the parties wish to increase the principal amount of the
Amended Note by Four Million Ninety-Eight Thousand Three Hundred Nine and 00/100
Dollars ($4,098,309.00) in order to effectuate the purchase price adjustment
described in Section 1(g)(vi) of the Purchase Agreement for the Company's fiscal
year ended December 31, 1998.

         WHEREAS, the parties wish to amend the terms of the Amended Note
pursuant to the terms and conditions set forth herein below.

         NOW, THEREFORE, in consideration of the facts recited, the covenants
contained in this Amendment, and for other good and valuable consideration, the
receipt and sufficiency of which consideration are hereby acknowledged, Navistar
and the Company hereby agree as follows:

         1.       Effective as of the date hereof, the Amended Note is hereby
                  amended to be in the amount of "$19,920,150.00."

         2.       Effective as of the date hereof, the first paragraph of the
                  Amended Note is hereby amended to its entirety to read as
                  follows:

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                  FOR VALUE RECEIVED, Core Materials Corporation, a Delaware
                  corporation (the "Company"), hereby promises to pay to the
                  order of Navistar International Transportation Corp., a
                  Delaware corporation ("Navistar"), the principal amount of
                  Nineteen Million Nine Hundred Twenty Thousand One Hundred
                  Fifty and 00/100 Dollars ($19,920,150.00) (or the unpaid
                  principal amount from time to time outstanding hereunder)
                  together with interest thereon calculated from the date hereof
                  in accordance with the provisions of this Note.

         3.       The Company hereby ratifies and confirms the Amended Note, as
                  amended hereby, in all respects; and, as amended hereby, the
                  terms thereof shall remain in full force and effect. This
                  Amendment may be attached to and shall form a part of the
                  Amended Note for all purposes.

         IN WITNESS WHEREOF, this instrument is executed as of the day and year
first above written.

                                     CORE MATERIALS CORPORATION

                                     By: /s/ Kevin L. Barnett
                                         ----------------------------------
                                             Kevin L. Barnett
                                             Vice President, Treasurer &
                                             Chief Financial Officer

                                     NAVISTAR INTERNATIONAL TRANSPORTATION CORP.

                                     By: /s/ Thomas M. Hough
                                         ----------------------------------
                                             Thomas M. Hough
                                             Vice President and Treasurer

                                                                              44<PAGE>   1
                                                                   EXHIBIT 10(M)

                           CORE MATERIALS CORPORATION
                     1999 INFORMAL CASH PROFIT SHARING PLAN

         Core Materials has an informal cash profit sharing plan for its
management and salaried employees which is calculated as follows:

         A profit sharing pool is created after a reasonable return is provided
to stockholders.

         Annually, the Company's Board of Directors will establish thresholds
for Earnings Before Taxes ("EBT") to provide such return to the stockholders.

         A profit sharing pool will be created based upon percentages of EBT
above the thresholds which will be shared with the permanent salaried employees
in the form of profit sharing.

         A total profit sharing pool is limited to a maximum percentage of EBT
as established by the Board of Directors.

         The salaried profit sharing pool is split into two groups, an
"executive" group and a "salary" group. The executive group consists of the
Chief Operating Officer, the Chief Financial Officer, the Vice President of
Sales and Marketing, the Controller and two other key management positions.

         The executive group shares in 40% of the pool while the remaining
salary group shares in 60% of the pool.

         Employees must have been employed as of December 31, 1999 to be
eligible to participate. There is no pro-rating for terminated employees.

         The Board of Directors reserves the right to change the plan annually.

                                                                              45<PAGE>   1
                                                                     Exhibit 4.4

                               December 30, 1999

R. G. Barry Corporation
13405 Yarmouth Rd., N.W.
Pickerington, Ohio 43147

Mailing Address:
P. O. Box 129
Columbus, Ohio 43216

          Re: Response to Request for Consent Regarding Revolving Loan Agreement

Ladies/Gentlemen:

     The undersigned banks (the "Banks") are lenders under a Revolving Credit
Agreement entered into with you as borrower (the "Borrower") dated as of
February 28, 1996 (the "Agreement"). You have requested that the Banks consent
to the existence of a violation of Section 9.5 of the Agreement for the fiscal
period ending January 1, 2000.

     The Banks hereby agree that the failure of the Borrower to satisfy the
requirements of Section 9.5 of the Agreement for the fiscal period ending
January 1, 2000, will not constitute an Event of Default as defined in the
Agreement, provided that each of the following conditions is satisfied by the
Borrower:

     1. The Borrower executes and delivers a copy of this letter to each of the
        Banks on or before January 1, 2000; and

     2. There exists as of January 1, 2000, no Event of Default, nor any event,
        condition or failure that, with the giving of notice or lapse of time,
        or both, would constitute an Event of Default, other than a failure by
        the Borrower to satisfy the requirements of Section 9.5 as of January 1,
        2000, and there exists no Event of Default thereafter; and

     3. The Borrower pays to each of the Banks, their pro rata share of a
        consent fee in a total amount equal to one-quarter of one percent of the
        aggregate amount of the Commitments, as defined in the Agreement, with
        50% of the consent fee payable prior to January 1, 2000 and the
        remainder due upon the consummation of an amendment during the first
        quarter; and

     4. The Borrower pays the reasonable fees and expenses of the Banks' counsel
        relating to the review and granting of the consent described in this
        letter.

This letter agreement may be executed in any number of counterparts, all of
which taken together shall constitute one and the same agreement, and any of
the parties to the Agreement may execute this letter agreement by signing any
such counterpart.
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R. G. Barry Corporation
December 30, 1999
Page - 2 -

                                   THE BANK OF NEW YORK
                                   /s/ William Barnum
                                   ------------------
                                   By: William Barnum
                                       --------------
                                   Its: Vice President
                                       ---------------
                                   One Wall Street -- 8th Floor
                                   New York, New York 10286

                                   THE HUNTINGTON NATIONAL BANK
                                   /s/ R. H. Friend
                                   ----------------
                                   By: R. H. Friend
                                      -------------
                                   Its: Vice President
                                        --------------
                                   41 South High Street -- HC0810
                                   Columbus, Ohio 43287

                                   BANK ONE, Michigan
                                   /s/ Thomas E. Redmond
                                   ---------------------
                                   By: Thomas E. Redmond
                                      ------------------
                                   Its: Managing Director
                                       ------------------
                                   P. O. Box 710170 -- OH1-0170
                                   Columbus, Ohio 43217-0170

Acknowledged and Agreed:
                                   R. G. BARRY CORPORATION
                                   /s/ Michael Krasnoff
                                   --------------------
                                   By: Michael Krasnoff
                                      ------------------
                                   Its: Vice President - Assistant Treasurer
                                        ------------------------------------
                                   Date: December 30, 1999
                                         -----------------

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