How to replace differential bearings on a 2002 gmc sierra 1/2 ton pickup

1. jack up the truck and support the axle with two jackstands
2. remove your wheels, differential cover(use an oil pan for fluid is going to spill everywhere)
3. remove your roll pin, it has a small bolt (use 1/4 inch drive with socket to save yourself from living hell)  (inside the gear carrier with the four small gears (it is ok to spin the axle at this time (remove your driveshaft or chauk the wheels and put the car in 2 wheel drive and in neutral)
4. after the pin is removed, DO NOT SPIN THE AXLES, push the axles toward the differential, remove the "C" clips at the end of each axle shaft, then slide your axles out of the axle tube.
5. now, unbolt the two carrier holding clamps (4 large bolts) and carefully remove the carrier, on each end of your carrier should be 2 out of the four bearings that could need replacing. (note that without specialized precision tools this will be impossible to reassemble correctly, this is concidered to be an "A" grade technitian's job in the work force) (reply back if you want a list of tools and tests you will need in order to get your differential working again)
6. remove the driveshaft if you havent done so already and unbolt the pinion gear nut (hidden inside the driveshaft yolk attached to the differential) (an impact gun is recommended because the pinion will spin and if you try to hold it, it will cut open your hands) then carefully slide the pinion out of the large opening in your differential.
7. the last two of four differential bearings will be here, previously supporting your pinion gear + shaft. they will fall out but you will need a brass punch and hammer to remove the outer bearing races that have been pressed into your differential.
8. clean the now open differential cavity plus gears with brak-kleen or other grease and oil remover then wipe clean with a lint free rag.(inspect for any damage and replace if nessisary)
9. hammer your pinion gear races in EVENLY and in the right spot, double check that everything came out in the same order that your about to put them in.
10. install new bearings and find (i couldnt tell you where) a new crush collar for your pinion gear.
11.after your pinion bearings are in, put your new pinion oil seal into the differential (a wooden board or any other flat stock will help) and hammer in evenly. (oil the seal before installing)
12. take off the old crush collar and install the new one (note the size difference)
13. when the pinion is in, reinstall the driveshaft yolk and tighten the pinion nut to 250-350 foot pounds (no you do not need glasses, you read that correctly)
14. (here is where the presicion work begins on your new differential) if you want to take it to a professional i do not blame you. if you really feel you can do this on your own, ask for the last 10-20 steps and ill gladly give them to you.

Hope this helps!
                       Joe.

Place axles on jack stands. Remove tire & wheel. remove axle bolts on end of axle. Remove inspection cover on housing. Locate and remove either C-Clips on alxes . Pull axle out far enough to remove bearings and replace in reverse order I am assuming the ring and pinion are in good condition. But always check for burning, stress cracks and shims while inside casing. Make sure you clean casing out with break clean and full with fresh gear lube oil. Don't skimp on quality a few more dollars will save you in the end