Here is an Install Guide for Changing the Rear Axle Seal.
Vehicle in 2002 Chevy Duramax
This is what you'll need: Seal, wheel bearing locknut socket ($10.00), and brake cleaner (multiple cans, I used 3). You can these at your local parts store.
Here is the wrench you'll need for the axle nuts.
Remove the 8 bolts that hold the axle with a 3/4 socket, then carefully remove the axle. It has a gasket on it that you don't want to tear.
Here is the hub after the removal of the axle.
Remove the caliper. It took an 18mm socket. Leave the brake line attached.
Remove the rotor. It just pulls off.
You are now down to the hub, and you can see the parking brake shoes which are likely to be covered with gearlube.
Here is another shot of the parking brake.
Remove the snap ring. No special tools are required.
The snap ring keeps the key for the axle nut in place.
Remove the key. It just slides out.
Here is the axle nut after removal with the special socket.
Here is the spindle with the emergency brake after the removal of the hub. The hub just pulls off.
We used a brake adjustment tool to pry out the seal. Seal pullers can be purchased.
Remove the seal with very small and careful prying, turning frequently.
Here is the hub with the seal removed.
Here is the seal.
We used a piece of wood to protect the seal as we tapped it in place carfully with a hammer.
Here is the new seal installed in the hub.
The rotors are vented. It is likely that you will have gear lube on the rotor, inside the emergency brake surface, and inside the vents of the rotor.
It took a lot of work to get the rotor clean. The key to cleaning a heavy build up of gearlube is to have scraping tools, several cans of brake cleaner, and lots of paper towels. Wet with brake cleaner, wipe, and get a clean towel. If you don't change paper towels often, you'll just smear gearlube over the same areas, over and over.
Slide the hub back on the spindle.
Start screwing the hub locknut back on.
You'll use a wrench and the special axle nut socket. Torque to approximately 50 ft lbs while rotating the hub counter-clockwise. This seats the hub.
After seating the hub. Loosen the axle nut, adjust it finger tight and align it so you can slip in the locking key that keeps the nut from moving.
Re-install the snap ring to hold the key.
Slide the cleaned rotor back on making sure it is seated as pictured.
You are now ready to re-install the caliper.
Re-install the caliper. I used thread lock on these bolts.
Slide the axle back in after you clean it off. (just a wipe down will do) Re-install and tighten the 8 bolts. I used thread sealer on these too.
This DIY is from DP