Hard to tell, is that mainly the exhaust or have you isolated the just the noise? If isolated, sounds like dry/worn bearing. If exhaust, can't hear anything but the exhaust.

 

Grinding is hard to hear in my video, it's louder in person.
I agree it sounds like a dry/worn bearing. I've ordered new u joints.

 

Closing this out. Grinding noise turned out to be the front pinion bearing. The metal shavings from the bearing wear stayed in the front part of diff and never made it to the gear oil reservoir.
I replaced the pinion seal, wheel bearings, wheel seals, and drive shaft u-joints before facing reality.
I had to cut the bearings to get them off of the pinion. They were on tight and basic bearing puller couldn't budge them.
Replaced the pinion and carrier bearings and races. I was expecting the re-install to be a nightmare, but I got lucky. I had to buy a special tool for the side adjusters, but everything else was in tool loan program at auto parts store.

 

Next time, pinion in the freezer and bearing warmed up.... slides right on.

 

Nice and quiet now?

 

for now, but I did it and its my first so....

 

getting the bearing off was the hard part. Bearing pullers had lots of torque on them and no movement so I pulled out the dremel.
Putting the bearings on was not bad.

 

I completely ruined a $100 puller trying to get the bearing off a chrysler 8-3/4 pinion... I'm not sure what kind of puller is needed, but probably not going to rent it. Glad you got it back on the road !