AMENDMENT NUMBER 2 TO
                           TOP AIR MANUFACTURING, INC.
                                STOCK OPTION PLAN



         WHEREAS, Top Air Manufacturing, Inc. ("Company") has heretofore adopted
the Top Air  Manufacturing,  Inc.  Stock  Option  Plan  (the  "Plan")  effective
November 6, 1992; and

         WHEREAS,  Article VIII of the Plan permits the amendment thereof by the
Board of Directors of the Company (the "Board"); and

         WHEREAS,  effective  October  1,  1995,  the Board  authorized  and the
Company adopted an Amendment to the Plan; and

         WHEREAS,  the Board has this date authorized a further amendment to the
Plan to  increase  the  aggregate  number of shares of stock which may be issued
under the Plan;

         NOW,  THEREFORE,  the Plan is  hereby  amended  by  deleting  the first
sentence  of Article  III of the Plan and  substituting  the  following  in lieu
thereof:

                  "The aggregate number of shares of stock which may be
         issued under the Plan shall not exceed four hundred twenty-
         five thousand (425,000)."

         This Amendment shall be effective as of the date hereof with respect to
all options granted under the Plan.

         IN WITNESS WHEREOF, the Company has caused the Amendment to be executed
this 4th day of March, 1997.


                                          TOP AIR MANUFACTURING, INC.



                                          By:    /s/ Steven R. Lind
                                          Title: President