I got a rearend out of a 66 chevy truck. I got the widest tires my fenders can handle on the ends and the rear is not narrowed or anything. It has a 3.73 rear which was built for a small block chevy. I just welded some mounting pads on the rear end, turned my leaf springs around to center the rear correctly and even my parking brake cables hooked up easy. This rear has the same 6 lug bolt pattern as stock and uses the same wheel cylinders as your stock AD rear. To me it is the perfect swap and you get to stay all GM. Mine holds up to about 275 hp and i have never worried about it. Good luck.