Seals are 1960 to 1964 with the flanged output shaft. seal changed in 1965, still had the flanged output shaft. Seal changed again in 1966 to the slip spline output shaft. I'm not sure if it ever changed again. As for Fatsco, having the seal, I called them before posting, to get the part numbers, pricing, and make sure they still had them. Their trans kit, has extra parts to cover expanded years.