Are rear seats interchangable on all A-bodies?

So basically, any A body rear seat 2 door model will work/interchange and fit but tabs may be different due to years?

no way! Try fitting an early A body seat in there, not even close. Then there’s the fold down seat from 64-66 Cudas, convertibles are different in both the upper and lower. Stuck with the make and model you have, and get as close to the year you have.