I Just got a 8.5" 10 bolt GM posi unit that is 30 spline, will this work in my 74 10 bolt, as long as i buy 30 spline axles?

Thnaks

 

depends if the ring gear was the same ratio
i had a 3.42 open diff that i put a stock posi from a 2.92 gearing and it is shimmed all the way to one side almost and i had to cut the drum on one side for it not to rub on the back plate.
so i don;t suggest that, but when i was 18 i made it work

 

If you buy gears from Richmond you can put whatever gearing you want in it and not shim. Richmond makes them for various size 10 bolts to work without the shimming.
Page 220 of Summit Racing's catalog.

 

thanks gears bought ...now just need the axles