i am currently swapping a dana 44 rear into my 1991 formula....the rear came from 1988 gta....now the gta was a 9bolt rear originally but brakes were swapped over to dana44....i havent yanked my 1991 rear just yet but the 88 rear is sitting on my floor....i know ive read somewhere that in 89 rear disks were made larger but i cant seem to find that now....i measured rear disk on dana44 and they are 10.5"

any help would be great!

 

well, i read somewhere that rear disks on 1991 are 11.5"......can someone verify this for me....also, is there a larger difference between disk brake setups....just trying to solve problems before i start swapping...

 

The '89-'92 rear disc brake setup is much better. It is commonly refered to as "the one with 12" rotors", although they are not actually 12". Bigger rotors=better braking.