i have a 02 2500 ram van and the rear end howls. i juust put 75w synthetic in it and the additional additive. there was no metal in it and the magnet on speedometer sensorr was fairly clean. the synthetic and the additive helped a little. any causes known and or suggetions would be helpful.thanks!!!!!!!!!!!

 

It's either a worn bearing or worn gears. There is no way for you to get around doinga rebuild or swap at this point.

 

I would inspect the rear bearings first. Usually those are the problems for the howling vs. the grinding if it's the gears. However, how did the gear teeth look while working in there?