I'd do a SD axle--I hate the fact that the rear is a smaller stance than the front. PLus you get rear disk brakes--though I have heard mixed reveiws from people-something to do with the proportioning(sp?) valve on the OBS. What gearing do you need? I just picked up a 10.25 with 4.10's for the truck. My 3.55's are killing me towing, so i will have that axle for sale soon