The gear ratio cut-offs for the differnent carriers depend upon whether the carrier is a posi unit or not. I'm searching in the archives and FGF's for the splits.
For quite a while, only Richmond gear has offered new gear sets for our FGF's but only from 3.55 and up (to 4.33 I think). I saw some discussion recently over on Performance Years about somebody who was looking at making lower ratios for the BOP 8.2 and testing the waters to see what kind of interest there was.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
