Rear wheel diff oil seals

80-90 oep diff oil unless it is a limited slip diff in which case you use special limited slip diff diff oil
don't know if it is limited slip diff diff
you can check by jacking up the rear end and having a friend turn a rear wheel
by holding one wheel the other wheel will be turning in the forward direct as that is what limited slip diffs do diff do ( both drive )
other than that call your local manufacturer service center and ask

It sounds like it could be in the rear diff not the bearings normally they make a roaring noise. Have you tried cleaning and adjusting the rear brakes. I would try that and see if it helps

You don't say, Front or rear wheel drive. First check oil level, On rear wheel drive check the thrower plate on the tail shaft at the diff end is not bent and rubbing on the seal, A dry oil seal can make this noise.so can the U/Joints. on front wheel drive , check the cv joints , dry oil seals , the drive shaft inner cv joints have a thrower plate that may be bent. worn or binding brakes can make this noise also.

I wonder if you have a posi. rear diff. and they didn't put the proper grease in the diff. or didn't put additive in the grease. Without the add. the clutches in the posi. slip and clatter.

diff overheating is from incorrect mesh of the crownwheel and pinion
that can be from too little clearance , too much clearance of failing bearings and too much preload on the pinion bearings
it can also be from incorrect oil level in the diff to the bottom of the threads of the fill plug
it is time to pull the diff and check the bearings
the problem will most likely be the bearing behind the pinion as that one takes all the load
diffs normally run hot but it is the escaping oil that is the problem
that could be from bearings on the pinion allowing the lip of the flange seal to not seal properly

If you can see inside the wheel bearings then they require lubrication from the differential. If they are sealed then no. You don't say if the rear axles are 1/2 ton or 3/4 ton. No brand of seal will seal better than any other. Spray engine degreaser in the rear end and flush out with water. You may need to do that more than once.

Raise the vehicle and properly support it. Remove the wheel and drum. Remove the rear diff cover, have a drain pan underneath to catch the gear oil. Place the trans in nuetral, chalk the front wheels to keep vehicle from moving if you forget to put it back into park befor you lower the vehicle. Rotat the differential until you see the bolt that holds the diff pin in place. Remove the bolt, 5/16 or 8 mm I believe. You can then remove the diff pin, do not rotate the diff with the diff pin removed! Push the axle in, you can then remove the C-clip that holds the axle to the side gear, it will usuall drop or just fall out. Pull the axle out of the rear diff and replace the seal. Put everything back together. Use black or grey RTV to reseal the diff cover making sure o clean up both surfaces as best you can. Put trans in park. Lower the vehicle. Remove the fill plug from the side of the differential and fill with gear lube until lube comes out the hole. Reinstall the plug and your good to go. Let me know if you have any questions and I'll do my best to answer them. Thank you for using FixYa.com!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

check diff oil see if metal fillings or not
sonds like diif on way out
input to diff tight or sloppy
any oil in it
check wheel end for seal leaking or slopp
axel bearing worn out

Jack it up, put it on stands. Remove the wheel, the brake drum, the differential cover, the axle clip, and pull your axle. Remove and replace the seal, install new diff gasket, re-install, and refill oil.

It is fairly easy to do. remove rear wheels and brake drums, remove the differential cover, rotate the diff to access the diff pin bolt and remove, remove pin, push axles inward and remove c clips, slide out axles and replace seals. reverse procedure