My rear diff was leaking gear oil bad (like, 2 quarts a week) so I decided it was the pinion seal and set out to fix it.

The new seal, made by Timkin was purchased from Auto Zone for $5.99.

Step 1, chock the wheels, drain the diff fluid
Step 2, use chock to make a line accros the driveshaft, pinion flange and diff
Step 3, use 14mm wrenches/sockets to remove the 4 driveshaft flange bolts
Step 4, pull the driveshaft twords the front of the 4x4 and down to get it out of the way
Step 5, use a 30 mm sicket to remove the pinion nut
Step 6, pull the driveshaft flange off the pinion gear
Step 7, use a hammer and sctrewdiver to remove the old seal, this was kind of hard (be careful not to damage the pinion gear)
Step 8, lightly grese the new seal around the edge
Step 9, tap the new seal into place with a pice of pipe and a hammer
Step 10, Replace the pinion/driveshaft flange (in line with mark on diff)
Step 11, Replace pinion nut (make sure the pinion washer does not fall off)
Step 12, Put driveshaft into place (in line with all marks) and slide in bolts
Step 13, Tourque down all 4 driveshaft flange bolts
Step 14, Fill er' up with gear oil (appx. 3 quarts, 90 weight)
Step 15, test drive, feel/listen for vibration, when you get back home it should not leak any more!

Took about 1.5 hours, a 14mm wrench, 14mm socket, 30mm socket, flathead screwdriver, hammer, greese, gear oil, wheel chocks and a lot of soap to clean up afterwords. Any questions, hope this helps some other people.

Lamm

 

You should be sure and unstake the lip of the pinion nut before removing it (bend the dimple out of the slot in the pinion shaft) and then be sure to re-stake it afterwards using a center punch. Be sure and get the staked spot back into the groove so you get it back to where it was before. That way you don't change the pre-load on the pinion bearing.