8.5" 10 bolt rear diff rebuild

[Nathaniel2g]

Whatever you do make, sure you can get your diff spill to fill drain plug out BEFORE you crack open that rear end. They use a 3/8" ratchet head and are not very deep. They round off super easy and once they're rounded off your only option is to weld. If your rear end looked anything like my (slight surface rust and about 3 layers of undercoat) it will take you an hour of grinding just to get the weld to stick properly. Also, make sure you have 3 quarts of 80W-90 gear oil on hand to refill once you're done.

 

[Ironhead]

Nathaniel2g makes a real good point about being sure you can remove the filler plug BEFORE you take the back off the diff. One other point is that it is really worth it to remove the spare tire before you get into this, that way you have a bit of room to move around, and can see better what you are doing.

 

[5speed91]

You can do this. Its pretty easy and straight forward. I just did it on my Caprice which has the same diff. There are many U tube videos on how to do this properly. One other thing to remember is try not to rotate the drive line/ or axles one you pull the axle shaft(s) out or the spider gears will fall out complicating your procedure. Its not the end of the world if they do but just makes it harder to reassemble. O'Reilly rents the bearing puller and the bearing installer. Also make sure you clean the axle tube housing really good while the axles are out. If your bearing has been bad for a while, it will likely have chewed up the axle shaft requiring replacement and may have deposited metal shaving in the tube. If you need a new axle, go with quality brands. You can probably still get GM shafts but if not, I no you can buy Moser axles for these trucks.

 

[sewlow]

The one part that is apparently no longer available from GM is the carrier center pin. They do like to wear & that can cause probs such as mysterious clunks & grinding noises. Especially with an Eaton style posi but open diff.'s can suffer from the same. Not aware of any aftermarket producers. You may get lucky if the dealership parts guy can find an N.O.S. part via a nationwide search of GM dealers. There could be one or two, maybe a whole stash of them, on a shelf somewhere in a one-horse town's dealer's part dept.

 

[Jorge6.5]

How about a swap to a 14sf?