I put a 3rd gen Camaro (1985) 3.23 ratio in my 55 2nd. It is the right width, but is a long way from being a bolt in. I cut all the brackets off and ground down the welds, then welded new spring perches. Driveshaft worked and emergency brake cables hooked up. It made a good installation. I put disc brakes on the front to match up all the bolt patterns.

Hugh