What did G.M use for gears and gear diameter on ;69 firebirds? Mine is a stock rear end with I believe 3;23 gears in it and I want to put a posi unit into it. I was wondering if they are all 8.2 27 spline units or if they did some other things.

There are also 8.5's, but not for FG BOP. There are different carriers for different ratios. I'll be doing the same thing to a spare 3.23 open diff. I hope to get that done next year.