Originally Posted by SpectorV
i belive your 64 has leave springs you may can swap the components and keep the hulls where they are....
You do not mean the housing? The 66 is an 8inch and the 90 is a 8.8. There was a 7 1/2 in the family somewhere, but I think it was on V-6's They do make kits to do a 8.8 to a classic platform, which is really inexpensive if you compare to the 9 inch. You can pick up an SN-95 with disc brakes and save money on a rear disc swap.