Factory posi install
 

I'm not opposed to a full rebuild but my 70 has a factory open carrier with 3.73. I've got a posi unit with 3.73 ring gear out of a 67 with all the bearings and shims. What's the chance that it'll drop in with minimal shimming required?

Re: Factory posi install
 

If you can drop in both the ring and pinion from the posi unit, your chances would be better. No guarantee it will work but it should be close and easy to dial in by checking pattern on gear teeth.
As far as using your 70 pinion with the 67 ring gear this is not recommended as the ring and pinion wear in to each other over time.

Re: Factory posi install
 

You beat me to it. Lol

Re: Factory posi install
 

What about bolting my 70 ring gear to the 67 posi carrier? This going to get me into a total re - setup more than likely?

Re: Factory posi install
 

Yes bolting your 70 ring gear would be ok and might get you close. You will still have to check the tooth pattern. You might get lucky.

Re: Factory posi install
 

Here is a link to help you pattern the gears. Also don't forget to check backlash. http://www.sierragear.com/ring-and-pinion-gear-pattern/

Re: Factory posi install
 

Hopefully it'll be in the ballpark and just need some tweaking. I've set up a couple before but it's an all day affair for me from scratch and I was just hoping to avoid that. Thanks guys.

Re: Factory posi install
 

You'll be fine with your old ring and pinion. Just set your backlash and add a couple thousandths extra on each side for some preload.

Re: Factory posi install
 

Thanks

Re: Factory posi install
 

Years ago I bought a 8.5" rear axle for my 79 malibu. The axle came out of an early 80's 442. It was 3.73 open the p o had a posi but was scared to install it. It went in with minimal fuss. Btw the way i know the axle was in fact out of a 442 was only the 442 came with 3.73. Posi was optional. Buick GN had 3.42 posi. I understand the 8.5" rear behind the Buick 3.8 turbo, but why behind the 307 Olds but not behind the 305 in the Monte SS?