[wecycle]

2001 4x4 with a whine from the front diff when under power. It goes away when coasting.
What could cause this and how can it be silenced?
I topped it off with 80w-140 gear lube with no change. I was about 6 oz low.
I do not know if the gear lube has ever been changed.

 

[Tymont]

I would start by changing the gear lube completely. Clean the housing out real good while you have it open.