Please help diagnose this noise

My 98 s-10 2WD 4 cyl with 135K miles has been making this grinding noise in the rear. Sounds exactly like grinding from really worn out brakes.

video 1 with wheels on https://www.youtube.com/watch?v=NzsD_7WKLX0&feature=youtu.be
video 2 with drums off https://www.youtube.com/watch?v=TESTGUkV404&feature=youtu.be

I can't tell where it's coming from. Both sides equal so I'm suspecting differential.
Shop looked at it and came up with bad U-joint and recommended differential service.
I fixed the u-joint. Fluid level ok in differential

You may want to pull the cover and look at the wear pattern on the ring.

You may want to pull the cover and look at the wear pattern on the ring.

probably will do that, but not sure what to look for

Pinion bearings are the most common failure in those diffs, that requires an overhaul, not usually a dyer job. Either way further checking as mentioned is required.

Pinion bearings are the most common failure in those diffs, that requires an overhaul, not usually a dyer job. Either way further checking as mentioned is required.

any guess as to cost to overhaul?
Who would do it. Transmission shop?
Appreciate your advice

First you need someone to check this out for a diagnosis, then check 4X4 specialty or drivetrain shops that are confident doing this type of work, done right it is about a 6 hour job.

I'm back and still baffled. I took off the cover of the differential to get a see inside. Didn't see any obvious wear or damage.
Also have what seems to be breaks dragging. Gets worse after driving for a few minutes. Will actually hold the truck on slight incline. Could this be related?

All this is true but the obvious is to pull the drums and inspect the brakes too. May be broken springs. Maybe bad wheel bearings. Check them for play in and out, up and down. Is there alot of play between the ring and pinion gears? Turn an axle and see how far it moves before the ring gear contacts the pinion gear in each direction,(the drive shaft will start to move). Check the pinion gear for play as well. Was the drained oil shiny and full of metallic matter ?

All this is true but the obvious is to pull the drums and inspect the brakes. May be broken springs. Maybe bad wheel bearings. Check them for play in and out, up and down. Was the drained oil shiny and full of metallic matter?

see videos, post 1

See if the brakes are dragging when this happens jack up the rear and try and turn the wheels by hand, see what happens.

See if the brakes are dragging when this happens jack up the rear and try and turn the wheels by hand, see what happens.

they drag a little but not enough to hold the vehicle on a slight grade

Just now looked at the videos. Camera moving too much for a good inspection. No noise with the drums off but they're loose ,not secured w/ nuts. That right side axle has some serious runout in video #2. Lets see the inside of the drums and the wear on the shoes.

Just now looked at the video. No noise with the drums off. That right side axle has some serious runout. Lets see the inside of the drums and the wear on the shoes.

shoes are new
video sound must not be clear. Noise is the same with drums on or off. Any way it could be a differential that is slightly seizing up?
Appreciate your time with me

Read my post #8.

Read my post #8.

I'll pull the wheels of again and check the bearings closer

What about the old gear oil. Was it shiny,full of metallics? wipe the inside of the diff case. Is there alot of metallic debris?

What about the old gear oil. Was it shiny,full of metallics? wipe the inside of the diff case. Is there alot of metallic debris?

there wasn't

If there wasn't any oil in it when you pulled the cover then you're back to post #3.

If there wasn't any oil in it when you pulled the cover then you're back to post #3.

everything looked fine. Found no metal or ground or chipped gears

My 98 s-10 2WD 4 cyl with 135K miles has been making this grinding noise in the rear. Sounds exactly like grinding from really worn out brakes.

video 1 with wheels on https://www.youtube.com/watch?v=NzsD_7WKLX0&feature=youtu.be
video 2 with drums off https://www.youtube.com/watch?v=TESTGUkV404&feature=youtu.be

I can't tell where it's coming from. Both sides equal so I'm suspecting differential.
Shop looked at it and came up with bad U-joint and recommended differential service.
I fixed the u-joint. Fluid level ok in differential

I think the drums are dragging due to little slack in the park brake cable or the cable is binding. also remove the drum rust on the brake drum edge next to the outer edge.