I'd want to rule out U-Joints before I tried to figure out why the diff makes that sound. If it took that bath I might pull the drums and clean out the breaks.

 

I appreciate all suggestions!

Yes it was 4-wheeled very agressively lately.

Guess I have a lot to tear apart and look over this weekend.

Scary cause I have to drive like 45 min away tomorrow night.

 

X2 on the back lash

 

so checked the rear brakes, cleaned them up super good and the noise did not go away.

All roads point to something in the diff. I called a place that does driveshaft/rear end work here in town an he was like prolly needs a new ring gear and pinion, starting price including labor is like $800, I was like WTF, do you charge like $200 hour labor, no thanks!! I could pull a whole rear end from a junk yard for less than half. He said good luck.

So now I gotta figure out how to fix this myself...bummer. No dial indicator or diff experience other than installing a lunch box locker.

 

Call another shop, or start looking on craigslist for an axle.