74 electra

[aaron]

What are the options for Diff ratio change in 74 Electra 455 Turbo 400 , Thinking maybe 3.5 or 3.7 ratio , are there options for it think its Posi , maybe diff out of another car ? What do you guys think?

[bob k. mando]

a 74 C-body should have the 8 7/8" rear end from Pontiac underneath it. the problem with this rear is that, like the Olds 9 3/8" which was used earlier, you can't get anything for it beyond bearing sets. no gear sets, no diff carriers.

i don't actually have OEM rear data for 1974 but i do have 1973 ( first year of the 8 7/8" ) and 1976. the shortest gear set available for that was in 1973(?) and was 3.42 in the small block B-Body GM cars. you'd be looking for LE ( limited slip ) or KE ( open diff ) code housings.

that's not the BEST answer though.

the best answer is to find a 1971-76 GM B-Body car with a small block engine. most of these have 8 1/2" GM rears under them and are a direct swap to C / D / E Body cars. once you've got an 8.5" rear all parts and pieces are supported by the aftermarket and you can get any gear set you want brand new.