I want to install a 57/58 complete (drum to drum) rear end in my 55 98 to get a 2.56 ratio. Hollender says it fits but no other details. Anyone made this type change and things to look out for besides shocks and u-joints? Thanks. Ron

 

Should work but run a tape measure from drum to drum on both rear ends to make sure. This was a common hot rod swap back in the day when a posi was needed in the 55-56 cars. 57 Old's and Pontiac were the first limited slip rear ends around at that time should be the same on a open or limited slip rear end.... Tedd

 

I think '58 was the first year for a limited-slip. Also, the later axles are larger and longer. If the '58 axles are the same as '57 then go for it. I put a '62 Poncho diff into my '57 housing and put in '63 Olds axles in, cut 11/16" shorter.