I’m planning to replace my original 1946 Chevrolet AK 4spd non-synchro “crash box” transmission, with an original 1946 3spd transmission. If I’ve researched correctly, this is a direct fit R&R. Is that correct? Any changes needed or are they an exact swap?

Care taker of a 1946 1/2 ton. Pretty much period correct original. Danny T, from B’ham, Al