Need help identifying rear axle 2002 Silverado 2500HD

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Spaxtix, Aug 12, 2014.

  1. Spaxtix

    Spaxtix New Member

    I have a 2002 Silverado 2500HD 4x4 6.0L

    RPO Codes: GT5 & G80
    Last 8 of VIN: 2E102085

    I'm trying to ensure I order the right parts so I need to know if I have 9.5, 10.5, or 11.5?

    I'm hoping for some identification tips without taking the differential apart ahead of time as this is the daily driver so it would be a weekend thing.

    I've rebuilt several rear axle assemblies of Fords and larger trucks with no problems but I'm not as familiar with Chevrolet.

    Anything like bolt counts, flanges, identifying features unique to the size, or if you just know the answer.

    Thanks for any assistance you can provide, it's really appreciated.
  2. silverado002

    silverado002 Rockstar 3 Years 1000 Posts

    Spaxtix try googling 2002 gm rear axle bolt pattern.
    I found 10 bolt, 11 inch wide is 8.25 and 8.5 gear. 12 bolt, 11 inch wide is 8.875 gear. 14 bolt, 12 inch wide is 9.75 gear. 14 bolt, 15 inch wide is 10.5 gear. May not exactly answer your question but you should be able to look through the pics i saw to help identify your axle. The codes you mention only indicate a 4.10 posi limited slip axle. Hope this helps ya.
  3. Spaxtix

    Spaxtix New Member

    I should have added that it's a 14 bolt pattern.

    I called several parts stores looking for rebuild kits and for the specifications I gave them they are only showing kits for a 9.5 and an 11.5.

    If it helps the transfercase is a NP 263 HD GM.


    Rear Axle
  4. Spaxtix

    Spaxtix New Member

    It is a 14 bolt. I've attempted to post pictures but it awaits approval from a moderator. Several auto parts sellers are only showing a 9.5 and an 11.5 given my vehicle information while attempting to find a rebuild kit.

    It may be that they simply don't stock a kit for the 10.5 and as such it's not showing in their systems.

    If it helps the transfer case is a NP 263 HD

    This link also leads me to suspect 10.5.

    My Rear Axle
    Last edited: Aug 12, 2014
  5. Conlan Rose

    Conlan Rose Epic Member 5+ Years 1000 Posts

    I agree it looks like the same cover listed for the 14 bolt 10.5. It also matches the pictures on that site. I know its not the 11.5 because those all have drain plugs and are mainly used for diesel applications.
  6. j cat

    j cat Epic Member 5+ Years 1000 Posts

    G80 is the eaton locker. GT5 is the 4.10 gear ratio and the 14 bolt cover is the 10.5 ring gear.. this is the typical GM 2500 rear diff..

    How did you damage this ? this diff requires fluid replacing with the cover removed and the proper synthetic lube.

    only time these break would be no lube get hot and the gears crack. 10.5 is very strong.
  7. Spaxtix

    Spaxtix New Member

    224,000 miles tends to cause bearing wear if nothing else. It's not broken yet but starting top develop some slop. It's much cheaper to fix these things before they break in my opinion. I would rather replace some bearings and seals than wait for it to start knocking teeth off and locking up. :rofl:
  8. j cat

    j cat Epic Member 5+ Years 1000 Posts

    so this GM vehicle is new to you. that explains the post you have made. these differentials last a long time the one you have should last the life of the vehicle provided you do your drive train fluid changes every 30-40K miles with the proper fluids gear oils.

    so I would replace the gear oil front and rear.. front uses the 80-90wt GL5 rear 75-90wt synthetic.

    on rear remove cover and inspect clean. check for cracks and gear mesh.. if the gears are good then you wasting your time replacing this ..

    the transfercase and transmission also require fluid replacing at 30-40K miles. transfer case uses tracII /// transmission requires dexron VI NOT DEXRON III !

    THE drivetrain on these do make clicking clunking from time to time this may be why they last so long.

    as the fluid ages you get more of this clunking.. I would expect another 100K on the diff..if the teeth look good..

    so lets say you do replace all this diff then you must break the diff in with no load or high power take offs for the first 1200 miles. then drop the cover clean inspect the gear teeth and now you can put the vehicle into heavy work conditions. most have trouble with these when new because the gear teeth wear in and harden as the vehicle is operated this causes a lot of heat if over worked then the teeth crack..

    typical failure with these is you will loose the locking on the diff. or the pinion will leak this is from owners not doing the fluid changes and cleaning...
  9. Conlan Rose

    Conlan Rose Epic Member 5+ Years 1000 Posts

    As j cat said GM rears usually last the life of the vehicle. To be honest its quit hard to really damage the ring and pinion of these trucks. When my spider gears/locker failed my R&P were completely unharmed even with metal shards floating in the fluid. As stated above the G80 can fail, most times it is caused by either clutches going bad or by the user not understanding how it works and gunning it the second it locks while stuck.

    My G80 failure was caused by the previous owner never changing the fluid, the clutches wearing out and one of my rear brakes seizing and locking a wheel at low speed. All those things caused the axle to semi-lock in low speed turns and every time it locked it took a tooth off a spider gear.

    Luckily you have a full float axle to you don't have to worry as much about axle seals or axle shafts as they are non load bearing only the axle housing its self is, unlike the semi-floaters on 1500 trucks.
  10. Spaxtix

    Spaxtix New Member

    The transfer case in my truck is a NP 263. I'm fairly confident that only the automatic NP 246 transfer case uses the Autotrac II fluid.

    I believe the NP 263 is considered a manual transfer case with an electronic shift. And the recommended fluid for it was Dexron III but Dexron VI is commonly recommended now as a replacement for the Dex III.

    Somebody feel free to correct me if I'm wrong.

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