[jhealey1967]

I've found a rear axle for sale out of a 1957 Oldsmobile that I'd like to put into my '55 Chieftain. It is my understanding that a '57 Pontiac axle is a drop in conversion for a '55. It is also my understanding that Pontiac's and Oldsmobile's shared the same differential/3rd member from '57 to '64. My question is—did they also share the same axle and axle housing? Or at the very least, did they in 1957? Same axle width, spring mounting, shock mounting, e-brake mounting on the backing plate, etc.? Any help would be much appreciated.

[radioburningchrome]

According to my 1950-1965 GM Interchange manual, the axle shaft for Pontiac fits only 57-58.The differential case interchanges 1957-58 Pontiac and Olds. Ring and gear interchange Pontiac and Olds 1957-63 w/ 3.08, 3.23, 2.87, 2.69 and Pontiac 61-63/ Olds 62-63 2.56.

FWIW the interchange also states differential case interchange for Pontiac/Olds as:

53-56
57-58
59-63

[Pontirag]

axle assemblies do not interchange between olds and pontiac

in 58 both olds and pontiac went to coil springs. So 57-58 dont interchange either.

My interchange book states that the rear ends for 55-56 pontiacs dont even interchange with 57 pontiac either.

Ford 9 inch !!! It even looks the same at a glance. PM me and I can tell you what to look for and to look out for.

[radioburningchrome]

Originally Posted by Pontirag

axle assemblies do not interchange between olds and pontiac

What interchange do you have?

[Bill Eveland]

If it's the same total axle width-about 60 1/2", it can be made to work. The spring perches can be added on, the shock bolts to the bottom leaf spring plate so reuse those. Also the housing end bolt pattern is the same so use your 55 backing plates also if the olds is differant.

[Pontirag]

Auto Interchange Systems,

1950-1965 Gemeral Motors Interchange Systems

3211 Robinwood Lane
Minnetonka, Minn.
55343

Published in 1979

[radioburningchrome]

Originally Posted by Pontirag

1950-1965 Gemeral Motors

Is that different from the General Motors?

I have the same manual printed in 1979, but the address is different:

Auto Interchange Systems
4048 Velarde Court
Las Vegas , Nevada 89120

Is it possible I have an incorrect version? It has a light blue cover, white spiral bound and a total of 230 pages.

[Pontirag]

Mine is green cover staple bound complements od J C Witney. Dont know the no of pages as it just got packed

mine has a few mistakes in it too. like 292 chevy six intake interchange info. price info is interesting reading