ford 9 inch gear problems
 

heres the scoop: i have a 86 ford f150 with a limited slip 9 inch and 3.55 gears but its too slow so i thought id switch in some 3.0 gears so i changed the front and when i went to put in the 3.0 gears...they wont quite mesh up properly...i have a currie 9+ housing if that makes a difference but my old gears fit\
to make the new ones fit i would have to grind the inside of the case where the ring gear bolts are when i try to move the carrier over to make the gears mesh right it hits the edge of the case.. is there small differences in the carriers to fit different size gear sets? i matches the 2 sets up and they seem the same depth and size.. im lost any help would be great
Cam