well what we usually do at the shop is put it on a hoist and get it to the speed that makes the noise and have someone under the truck listening for where its coming from. so if you have access to that then i would say that would be the best option to isolate the noise.

 

Alright so I pulled the drive shaft and one of the u-joints was totally screwed missing almost all the pin bearings.

That still didn't fix the noise but as I was under the truck I say that there is alot of oil leaking where the drive shaft connects to the axle so I think that bearing is gone.

 

that would be your pinion bearing, and it could be gone but you would have to pull the diff apart to see

 

Ya I talked to my old high school teacher and he's gonna see if he can get a new rear end for me.

With that ill be able to do some add a slight lift with some new leafs.

 

I'm in the same boat with the whining noise. I need a rear diff rebuild.