Help with converting b body 8 3/4 to A body 8 3/4 for my 1964 plymouth Valiant

Professor Fate said
Same size.
A body 8 3/4 rears weren't available before '66, so you will not find them listed for '65 and earlier.
But, the same dimensions apply for your car as the '66 and later cars.

Awesome ! Thats what my thinking was. Machine shop is waiting on me to confirm correct size with the 52 5/8 axles I left with the housing.

Thank you !!