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The G80 good or bad?

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by stchman, Dec 5, 2012.

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  1. stchman

    stchman New Member 1000 Posts 100 Posts

    I've never seen a GM truck with a drain plug on the differential.

    There are only 2 ways I know of to change fluid on a GM differential:

    Suck it out.
    Remove the diff cover.
  2. j cat

    j cat Active Member 1000 Posts 100 Posts

    well on the 2000 silverado and the others of this body type 4X4 the rear and front diff has drain plug ....
    with the rear EATON locking diff .which is standard with this equiped vehicle.

    also the diff has a tag which states what type gear oil to use. looking at the cover installed you will see a dimple in the cover. that is where the magnet is mounted.

    many gm vehicles do not have any drain plugs .... limited slip and the open type I have not seen plugs with the ones I have worked . those are on other vehicles like s10 / caprice etc.

    this is the torque spec for a 2005 .

    Some specifications from the 2005 GM (Helms) Service Manual for those that might do this in the future:

    Bearing cap bolts -55 lb ft
    Pinion shaft lock bolt - 27 lb ft
    Ring gear bolts - 89 lb ft
    Fill Plug - 24 lb ft
    Drain plug - 24 lb ft
    Propeller shaft bolts - 18 lb ft
    U-bolt nuts - 53 lb ft

    Backlash - 0.003-0.010" Preferred - 0.005-0.007"

    Pinion and differential case new bearing preload - 30-55 lb in
    Pinion and differential case used bearing preload - 25-45 lb in

    Pinion new bearing preload - 15-30 lb in
    Pinion used bearing preload - 10-20 lb in

    These specifications apply to the 8.6" rear differential only.
    Last edited: Dec 7, 2012
  3. stchman

    stchman New Member 1000 Posts 100 Posts

    I do stand corrected that GM front differentials have a drain plug, I was speaking about rear differentials.
  4. steved

    steved Former Member 100 Posts


    Some of the 2500/3500 series have a drain plug on the rear differential...actually quite handy as it makes changing the rear diff oil a breeze.

    Mine has one...I know that for sure...
  5. j cat

    j cat Active Member 1000 Posts 100 Posts

    look at the above posting I gave. you will see the torque spec for a 2005 rear diff drain plug is 24 ft LBS.

    this is from the helms repair manual.

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