Axel shaft hot

Seems like a bearing to me if your brakes are cool.
Check your end play in that axle once on jack stands, there should be a little play when pulling & pushing the axle,(you will have to check abodiesonly for tolerances). I think its .006”-.010” but don't quote me. If no issues pull the axle and inspect for heat colour,wear and smell for nasty toast.
Gear oil level ok? Should be since its only one side you say but never hurts to check.
Another thing to check would be that whoever welded the B body housing to an A maybe didn’t get the flange true/ straight. I have seen poorly welded flanges before and usually the axle is very difficult to remove and is holding the bearing wonky causing uneven load on the bearing.
If you have had the rear end in the car for a long time then the latter might not be the case.