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                                                                   EXHIBIT 10.4c


                                 THIRD AMENDMENT
                                     TO THE
                            STERLING CHEMICALS, INC.
              AMENDED AND RESTATED SALARIED EMPLOYEES' PENSION PLAN


                  WHEREAS, there is reserved to Sterling Chemicals, Inc. (the
"Company") in Section 15.1 of the Sterling Chemicals, Inc. Amended and Restated
Salaried Employees' Pension Plan (the "Plan") the right to amend the Plan;

                  NOW, THEREFORE, the Plan is hereby amended effective as of
November 1, 1998, as follows:

         1.       Section 3.2 is amended to read as follows:

                  "Early Retirement Date. A participant's "Early Retirement
                  Date" will be the first day of the month following the month
                  in which he retires from the employ of all the Employers
                  before his Normal Retirement Date, but after he has both
                  attained at least age 55 years and is vested pursuant to
                  Section 2.2. However, a participant who receives Post Benefit
                  Service credit pursuant to Section 17.4(a)(vii) will, upon
                  reaching age 55, be deemed to have terminated his employment
                  on having reached such date."

         2.       A new subparagraph (vii) is added to Section 17.4(a) to read
                  as follows:

                  If a participant between the ages of 54 and 55 is
                  involuntarily terminated by an Employer other than for cause
                  as part of a formal reduction in force or layoff program, the
                  participant will continue to receive Post Benefit Service
                  credit until he attains the age of 55; provided, however,
                  there shall be no duplication of Post Benefit Service that is
                  credited for the same period of time under any other provision
                  of the Plan.

                  All terms used herein that are defined in the Plan shall have
the same meanings given to such terms in the Plan, except as otherwise expressly
provided herein.

                  Except as amended and modified hereby, the Plan shall continue
in full force and effect and the Plan and this amendment shall be read, taken
and construed as one and the same instrument.

                  This amendment may be executed in several counterparts, each
of which shall be deemed an original, but all of which shall constitute but one
and the same instrument which may be evidenced by any one counterpart.

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                  IN WITNESS WHEREOF, the Company has executed this instrument
this _______________, 1999, effective for all purposes as provided above.

                                         STERLING CHEMICALS, INC.


                                         By:
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                                         Name:
                                                -------------------------------
                                         Title:
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