2003 Disco II.
I was driving down the highway and felt a big hesitation and then it seemed to drive fine. As I took my foot off of the gas to slow down, a deep whirring noise started. Putting my foot back on the gas made it go away.
I arrived at my destination and started investigating. As I shift into reverse and let it idle backwards, I hear a noise that sounds like gears clunking around and the car is jerking a bit as it idles back. Same in forwards.

I am having a friend bring some ramps over to my work so I can get under it and investigate.

Any thoughts?

 

I guess i'll be the first one to say....Have you rebuilt your front driveshaft? It should have zerks on each of the u-joints. if it only has a single zerg on the standard joint then get on that before it fails and rips everything near it apart.

 

If you want, I can send you a PDF file on how to rebuilt the shaft.
In the mean time, don't drive it.

 

front driveshaft was replaced a few months ago.
I am really leaning towards it being the rear diff that is making the noise, but I could be completely wrong!

 

can also drain the transfer case and open inspection plate. Has magnetic pin on the drain plug. Service diffs while under the truck, hope what comes out looks like oil without metal pieces.

 

Changed out the rear diff on Saturday and all is well.
Old one had no metal shavings or broken gears in it though.

 

Strange you didn't find any thing broken.

 

Not much oil came out of the diff. It was low for sure. Perhaps some bearings went bad.