I am literally going nuts here. I changed fluids in both diffs and the transfer case and it did sweet nothing. I am still driving it because I have to and nothing seems to be getting worse, just a recurring drill to my head. I did find that it doesn't start until you have been driving for about 3 or 4 minutes, it then occurs everytime you let off the accelerator and disappears as soon as you get on it again. If you let off the accel at the top of a hill and let the d2 gain momentum the noise increases with the momentum. It still sounds like the noise is from in the dash or right near the firewall on the drivers side but closer to center. ANYBODY, please help, listen to the noise a couple hundred times and help me figure it out.

 

As you can tell i am going crazy here. I have drain and filled tranny, differentials, transfer case and this noise still persists. If i shift into neutral while slowing down the noise almost goes away now. Please listen to it many times and see if you can get it. cheers

 

output?
bearing noise.
can you pull the front shaft and see if it goes away?

 

is your ac on? sounds like bearings are out on something, maybe the blower motor?

 

U have transfer box going bad

 

I would check for play in your drive train. Could be a worn crown and pinon gear.

 

That's a pretty cool noise.

Well, when you de-accelerate, the engine is twisting slightly and rubbing against something.

I venture to say---
You replace your engine mounts and it will go away.

you have something close to the crank harmonic balancer and when the engine moves just a bit down a hill - it rubs and makes that burrrrrrrrrr noise.

Or you have a drive shaft rubbing against a wire or a cat or a piece of that insulation around the cats.

Something like this is buggered up.

 

It sounds like transmission or the TC rubbing inside the bellhousing. My guess, and it's only a guess, is the torque converter or flex plate given up. The only other thing I can think of would be the front differential bearings. Sorry can't be more specific.