It seems like most people prefer to do this with the axle sitting in place under the Jeep, but I like to do as much as possible on the bench. There are several ways to go about it, but the one I've use with success is: Set your current axle on two parallel surfaces that are the same height, like some metal blocks tack welded to the welding table. You want the axle resting on it's perches(block up the center section to keep it's weight from causing the assembly to rotate off it's supports). Use a magnetic angle gauge to check pinion angle. Now take the axle off your new fancy jig and set the new perches back in the same spot on the supports that the old ones were resting, and set the new axle on them. Make sure you have the same distance from perch to backing plate on each side, and duplicate your old pinion angle with the angle gauge(or make adjustments from the factory setting that you recorded). Once set, weld the new perches in place.
