Actually had a few hours to call my own today and spent a little time working on the burb. I decided a few weeks ago to send both front and rear differentials to be rebuilt. They were both on the floor and both had 209K+ miles. Both have been completely rebuilt with all new parts. I stuck with the 4.10 gears and retired the G80 in favor of a Detroit TrueTrac. East Coast Gear in Louisburg, NC did the work and they also pressed in the new case bushings in the front for me.
Rear springs are buck under the truck, as well as, the 14 Bolt. I replaced the rear transfer case seal with a new GM unit before sliding the driveshaft back into place.