Also, the 4x4 and 2wd axles i believe are the same thing, i had 2 of them sitting next to each other, the 2wd being 2.94 and the 4x4 being 3.36 with e-locker, only thing i noticed differently was the 3.36 axle had a taller spring pad (to make the truck sit about an inch higher).
Other than that, no difference that i could see.