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It should be listed on a sticker located in your glovebox in the form of an "RPO code" which I will leave it up to the masters here to tell you which code you are looking for.
 

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I agree, you probably dont have 4.10's but you may not even have 3.73's.
 

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My 2001 1500 4X4 Suburban has 3.73's (pretty common) but that RPO code will confirm it for you.
 

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Rpo rear axle codes


G84-3.70
G90-3.15
G91-6.83
GHO-3.54
GH1-3.55
GN9-4.11
GSO-6.43
GT2-4.77
GT3-4.55
GT3-3.73
GT4-4.10
GT7-3.33
GT9-2.87
GU2-2.73
GU4-3.08
GU5-3.23
GU6-3.42
GU7-2.77
GU8-3.90
There are a lot more but my eyes are getting tired.

GU2 would be the 3.73 rear axel code.
GT4 would be the 4.10 rear axel code.
 

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My 94 Burb has the GT4-4.10 rear axel.

It also came with the factory towing so I am guessing here but if your truck came from the factory with the towing package most likely it has the 4.10 rear axel ratio.
 

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I wouldnt be surpirised if they were 3.55 in there
 

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The best way to tell if you don't have the sticker. or the badge on the diff cover is missing:

1. put vehicle in gear ("drive" if auto)

2. Jack up the rear of the vehicle (make sure that both rear tires are off the ground and please chock the front wheels and use jackstands!)

3. Mark the top sidewall of one tire

4. Mark a spot on the rear driveshaft

5. Have someone turn the tire one full rotation

6. Count how many times the driveshaft truned.

Example: If in one full rotation of the tire, the driveshaft turned 4 times, that means you have 4.10 gears; 3 and 1/2 times means 3.55 gears, etc..

Hope this helps
 

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Discussion Starter · #10 ·
not sure ill check on the info in the glove box but mines a 2wd with towing package and it has a locking rear diff if one spins faster locks the rear end and then open back up
 

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not sure ill check on the info in the glove box but mines a 2wd with towing package and it has a locking rear diff if one spins faster locks the rear end and then open back up
Chances are if you have the towing package you have the 4.10’s nut check your RPO codes in the glove box, then check my first post here for the RPO code.

GU2 would be the 3.73 rear axel code.
GT4 would be the 4.10 rear axel code
 

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Rpo rear axle codes


G84-3.70
G90-3.15
G91-6.83
GHO-3.54
GH1-3.55
GN9-4.11
GSO-6.43
GT2-4.77
GT3-4.55
GT3-3.73
GT4-4.10
GT7-3.33
GT9-2.87
GU2-2.73
GU4-3.08
GU5-3.23
GU6-3.42
GU7-2.77
GU8-3.90
There are a lot more but my eyes are getting tired.

GU2 would be the 3.73 rear axel code.
GT4 would be the 4.10 rear axel code.
I have the GT4 sticker in my 05 Suburban but I was told by the dealer it designates 3.73 not not 4.10 ???? :neutral:
 
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