Guys! Just joined this site to get this question answered. Recently purchased a 3rd Gen firebird rear and installed it in my 1949 Buick convertible. IT FITS!! However, the lug pattern on the 3rd gen rear is different from the stock 5" pattern that the buick had. I need those axles to retain the 5" lug pattern to run the stock rims. Short of CNC'ng the whole gammit, any ideas or direct swaps?? Any help would be appreciated.

Full size trucks have a 5 on 5 lug pattern, as to full sized cars, like the Impala SS.

To keep the 3rd gen axle you already have under there, you could get bolt on adapters, from Skulte.com, which are plenty strong.

Are you adapting the frame to the 3-link & panhard suspension, or putting leaf spring perches on the axle?

Axles can be redrilled to a different bolt pattern but they're very hard steel. If you redrill to a different bolt pattern, you'll also need to redrill the drum/rotor.

GM small bolt pattern is 5 on 4-3/4". You won't find any other axles to fit into that diff with a different pattern. 5 on 5" is the GM large pattern normally found on the larger cars like a B-body and on pickup trucks.

You can always replace the rims.

I would replace the rims, but I have to maintain the original look for the customer. I have the axles at the machine shop being drilled. Thanks for the reminder about the rotors, dropping them off today. I am maintaining the original panhard bar. Actually its a bar from Hotchkis for a 57 chevy that I lengthened. STRONG!! Airbags in the rear. I was hoping to find a direct swap.

Did you use the torque arm?

no idea what that is.

The torque arm is the big, long triangular piece bolted to the rear & slips into the rubber bushing that mounts on the tranny.

The car he's putting it in probably has leaf springs or trailing arms. The torque arm isn't required.

, but, you never know...