Here are a few oldies.

1966-72 c-body, 1966-72-b-body, 1970-72 e-body 383/440 engine mounting brackets are all the same.

1973 C-body disc brakes will fit 1966-1972 c-bodies.

1966-69 b-body k-members can be replaced with 1970-74 e/1970-2 b-body k-members for cheaper suspension upgrades and better handeling. 1973-74 e-body brakes use the cheaper rotors too.

8 1/4 and 9 1/4 will fit earlier 8 3/4 rears, bolt right on.

a-body 8.75 rears and early b-body rear will fit nearly perfect in 1930's street rods (unsure what models fit with what though).

1974-80 ramcharger/traildusters came with 15x8 rims and will fit nicely on rear of mopars with 4.5 bolt pattern.

there is probably another 60 items I can post, but don't want to let the thread die off yet.