The load/unload behavior is indicative of the inner carrier bearings (in the differential; the one that gets referred to as that on the driveshaft is the center bearing). Inspect the outer bearings first, naturally, since you have to pull the shafts to get into the 3rd member, but those should growl all the time if they're bad, regardless of direction.

~Adam


96 T100: D44, lockers and stuff