Oh, you have trouble. Ok, crawl under the back and remove the plate on the differential. It takes a 1/2 inch wrench or socket. You may have to pry the cover off after the bolts are removed. Catch the grease in a bucket. look for metal. It may be chunks or just "glitter" in the grease. You should be able to see any problems there. If everythings fine and no metal, jack it up, put it on stands and pull the wheels off. Shake the axles and see if there is play in the bearings. Look for any leaks around the seals. remove the brake drums if necessary (makes it easier). If anything is bad, there is a bolt on the carrier in the differential. It takes a 5/16 wrench or socket to remove it. Pull that bolt out and slide the main pin out. Push the axles in and remove the clips holding them in. The axles will now slide out. remove the four bolts holding the carrier in and it will pull out too. Now you can get to everything . be sure to check the pinion bearing for slack as well. Hope this helps. Luck.
It can be done, yes.
the rear end (differental)
No you do not.
3.73
Check if muffler is loose, check if rear brakes are worn out & grinding
The rear wheels are bolted to the axles. The axles run through the inside of the rear end housing.
80W90 gear oil.
yes
When I changed the fluid in mine it took 3 quarts to fill it up. Also if you have a posi-trac rear end you will need to put in a Posi additive. You can get it at Oreillys or AutoZone. If you don't put in the additive the rear end will make a clunking sound when turning.
It sounds like a universal joint to me, it's an easy repair and cheap too.
Probably your u joints or the rear end has too much slop.
I have mercury mountaineer 4x4 03 had grinding noise easy fix remove the shaft which connects the transmission to the rear end