Pulsating vibration while cruising??

Couple simple things to try that can really help. One, remove the shaft from the pinion and turn the differential 180* and reinstall. Two. Try to make sure the bearing cap retainers are in the back so they help center the joint. I also attempted to get both retainers in about the same position. Three, tighten all 4 bolts to spec. Finally, consider the reintroduction of the tail shaft counter balance weight.