Question for the "rearend guys". I've read here that universal gears for O rear carriers aren't reproed and verified that. However the GM parts book shows the pinion gear and shaft are the same part# as the 71-74 corporate rear. The diff side gears are a different part number, which makes sense since they have to be machined for the C-clips.
The tooth count is the same (10 and 16) on the O and corporate open carriers.
With the pinion gear being the same I'm thinking the odds of the 71-74 gear set working in the 70 O rear are better than zero. Can't think of a reason the C clip pocket would cause a problem. Any thoughts?
Thanks, Eric

 

The C-clip groove in the side gears isn't an issue as many folks have used the later 8.5" corporate posi units (410408) in the 71-72 rears that use bolt in axle shafts.

I do not know about the cross shaft and gear, but if the parts book shows the same number, then that makes a strong case for them being interchangeable. I recommend you contact monzaz if he doesn't see this and respond. (Jim @ JD Race.com) He does differentials for a living and would be the authority on this.

 

Are you talking about posi or Open diff?

 

It's an open diff. 1970, 3.23, code SE on the tube.

Thanks for the responses,
Eric

 

open diff spiders may very well be the same But the side gear spline will be different 12 '0' is a 30 degree pitch spline the 8.5 corp 1971 and newer is 45 degree spline both 28 spline.

Jim

 

Hmm. I see that on mine the pinion has a 45 pitch and the side gear a 30 pitch. Before I saw Jim's reply I went ahead and ordered a set that based on the pictures, has a 45 on the pinion and 30 on the side. I think everybody knows how reliable online product pics can be
So we'll know in a few days how it works out. It won't be the worst "unusable part" purchase in this project.
Thanks, Eric