I have a 1979 Firebird formula that has the 3.42 posi. Can it be swapped into my 1972 Cutlass? I know the firebird has the leaf springs and the cutlass has the coils under it. Someone told me that I could change that. Other than that would the rearend work?

Thanks, Mike

 

I think they are about the same width.
The different pumpkin is where you may have problems.
Measure the housings from the pinion yoke to the back side, and see if your driveshaft will still work before you go crazy with the welder. Conversion u joint may be needed in the rear as well.

Personally, I'd rather have the 72 bolt in axles than the metric C clip axles.
If they're both 8.5 rears, you can swap the guts, and keep your bolt in axles.

 

I'm with J on this. Swap the guts and keep your housing. It's not worth the money to convert a leaf spring axle for control arms.

 

The leaf-spring housing won't have the upper ears cast into it for the upper conrol arms. Just swap the guts,but get all of the specs on the gears before you remove them,so you can make sure they are the same when you swap into the other housing.Run some compound on them tto see what the current pattern is.As long as it is a good working rear,the pattern should be good.You will need to achieve this same pattern when they get swapped into the other housing.