12 bolt rubbing/grinding noise

[72c20customcamper]

Finished up the 68 and I was able to really drive it over 5 or 10 mph . Getting a resonating sound that’s definitely from the rear . Jacked it up and let her idle in drive I used the old screwdriver to the ear and it’s louder on the drivers side which is weird because it’s still there when I stop wheel from spinning but not as loud . I also checked the carrier bearing and it’s smooth and silent .

So I pulled the cover and nothing jumps out at me . No shavings in the oil gears look great . Thinking it may be an axle bearing or carrier bearing but like I said no fillings or glitter in the oil . I even swooshed a magnet through the oil and nothing . Pinion is nice and smooth too with no slop . The dark spots on it is oil dripping off . I rotated the pinion by hand and looked everything over looks almost brand new absolutely no wear .

Going to pull the drums tomorrow or over the weekend maybe something is rubbing on the drums IDK what else to check short of pulling the axles.

Any thoughts would be greatly appreciated.

[68Gold/white]

My thoughts....

Original axle bearings?
The rear most u joint always seems to take the most punishment. I’d pull the driveshaft loose and wiggle that joint around, spin the 2 free cups.....
The right rear axle is usually bad in all diffs I pull apart, look at it first.