I know its Ford but its the same set up, same collar so read this.
This is the time to inspect the axle bearing and cup for wear and to reset the axle bearing load. Make sure the bearing looks good, no pits in the cup or on the rollers. Make sure the backing plate, bearing retainer, and all shims and/or gaskets are clean. I select the shims needed to load the axle bearings to zero load. Zero is hard to describe. It's no bearing load and no end play. If you're not sure how many shims to use, follow the procedure in the shop manual to set the load. I think their procedure loads the bearings a little too tight, but it's worked ok for a lot of years, so who am I to question it. Zero load is desired, but if you're in doubt, a little too loose is better than too tight. Too tight will ruin the bearings. Too loose will let the seals leak again. Setting the axle bearing preload with the shims is a commonly misunderstood procedure. Remember you are adjusting the total preload for both axle bearings. The axles butt together in the center of the differential and have a tapered bearing on each outside end. The total number of shims determines the preload and each shim affects both axles equally. You're not setting each side, you're setting the total