I used a 12 bolt diff.out of a 1978 4x4 chevy suburban.it has 6 stud axles.also has 3:08 gears which is not ideal for me but I've been living wit has for 25 years. The width is a little wider than stock.when I measure diff width, I go backing plate to backing plate.when setting up your spring perches keep in mind the offset the torque tube diff has.you will need to build new perches to for accommodate this, otherwise the wheels won't be centered in the fenders. I built new perches other will use 2nd series55 and newer rear springs. These trucks use open driveshatft diffs and the springs are different.
