I am looking for a posi unit for a 7.5 innch ring gear 10 bolt im building. Are all GM posi carriers compatible with different ring gear sizes or do i have to have a 7.5 specific carrier?For example, will a carrier for a 8.5 ring gear 10 bolt fit a 7.5 ring gear 10 bolt?

 

It must be for the 7.5 and it must be the correct series for the gear ratio that you will be using. The 3.08 to 2.41 used a 2 series and the 3.23 to 4.10 used a 3 series. It also must have the correct splines for the axles that you will be using. Before '90 they were 26 splines and after that they were 28 splines.