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                                                                      EXHIBIT 18

        PREFERABILITY LETTER ON ACCOUNTING CHANGE FROM ERNST & YOUNG LLP


March 30, 2000


Terry L. Hall
Senior Vice President and
    Chief Financial Officer
GenCorp Inc.
Highway 50 and Aerojet Road
Rancho Cordova, California  95670

Dear Sir:

Note F of Notes to the unaudited interim condensed consolidated financial
statements of GenCorp Inc. ("the Company") included in its Form 10-Q for the
three months ended February 29, 2000 describes a change in its methods for
determining the market-related value of plan assets used in determining the
expected return-on-assets component of annual net pension costs and the
amortization of gains and losses for both pension and postretirement benefit
costs. The new accounting method includes changing the smoothing period from
five years to three years, changing the amortization period from approximately
12 years to five years, and the elimination of a ten percent corridor.

There are no authoritative criteria for determining a `preferable' method of
accounting for the manner in which realized and unrealized gains and losses are
included in the calculation of the market-related values of the Company's
pension and postretirement plan assets based on the particular circumstances;
however, we conclude that the change in the method of accounting described above
is to an acceptable alternative method which, based on your business judgment to
make this change for the reason cited above, is preferable in your
circumstances. We have not conducted an audit in accordance with auditing
standards generally accepted in the United States of any consolidated financial
statements of the Company for any period subsequent to November 30, 1999, and
therefore we do not express any opinion on any financial statements of GenCorp
Inc. subsequent to that date.



                                   Very truly yours,

                                   Ernst & Young LLP