On my 88 gmc sierra read differential locks up was told the pinion pin may be broken i would like to see a picture of the pinion and pin please

SOURCE: How does a GMC Anti-Theft Work?

anti theft in you gm vehicle is to prevent some body from driving away with your vehicle. Not to prevent someone from breaking into it. You need to have a secondary alarm system installed. This will protect the contents of your Denali. Mike

SOURCE: The radio on my GMC Sierra is locked. Does anyone

YOU CAN CALL YOUR LOCAL DEALER, GIVE THEM THE VIN # AND THEY CAN TELL YOU THE CODE AND HOW TO DO IT FOR FREE.. GOOD LUCK KEITH..

SOURCE: 2004 gmc sierra rear differential

remove cover.take off back wheels and calipers (or drums).turn differential to where you see small bolt/pin (5/16) horizontally (same direction as axles)on right side of differential.remove bolt/pin.A large pin (about 5"long 3/4"diameter) should slide out differential with ease ( you may have to tap one side of the large pin).turn differential to completely remove large pin.turn differential so you can see in the view window.push each axles in (they'll go in about 1 1/2"each) You may hear one of the axle C-clips fall.If not use a small telescoping magnet to remove the C-clips from the axles through the differential window.pull each axle out about 10"so they are out of the diff.Now remove the cap bolts(4-5/8"bolts) and remove the caps(mark the caps so they go in excactly the way they came out.be careful the diff might fall out.If not you may have to use a long bar or 2x4 to wedge and pry the differential out. Have a basket/crate w/rags in it to catch the diff.TIP:If you are removing the ring gear from the diff, the bolts are left handed bolts meaning you have to turn them clockwise to loosen and counter clockwise to tighten ; )

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SOURCE: how to replace differential bearings on a 2002 gmc

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.

SOURCE: need diagram to repair 2003 GMC Sierra spider

The bolts that hold everything in once out is very easy to replace. It islike removing a big turkey from the ovenwith the up most care.. The only trick is to remov the screw inside the pin holding the side gears in place which is inside the carrier housing