Do all 8.5" 10 bolts use the same differential?

[mc1984ss]

I have a posi carrier from a 79 8.5" 10 bolt. Is this the same differential as a grand national 8.5 or are they completely different?

 

[81cutlass]

Same.

Only difference is in 99 they went to a larger case bearing diameter to allow 30 spline axles, so if you put a later 30 spline carrier in an earlier case you need a special bearing.

But since it came out of a 28 spline car you can put it in a 28 spline rear G body axle.