You are looking at the main case for a 1964-65 Muncie 4 speed. It is cast # 3851325. This case contains the wide ratio cluster gear, pin and bushing. Correct for 1964-65 M20, M21 or M22 in all GM applications including Chevelle, Impala, Corvette, Nova GTO 442 and Buick GS. The case is stamped P0804. There is no vin stamping. This tranny no signs of ever being blown up. This is a good, solid case with no repairs or heavy ware. Ready to use.