8.8 whine and vibration

Check pinion angle. You may not have to get into the diff, but if you do you will want to check the spider gears, among replacing necessary items. I had a whine and some vibration and it turned out to be chipped spider gears. Also as stated, the new crush sleeve is necessary and must be tightened and checked with a beam style torque wrench. Diff would need to be removed from housing to replace the sleeve IIRC as the bearing gets pressed on/off. I also have been able to reduce/remove vibration from rotating the driveshaft as stated above.