2019 thru 2021 GM Half Ton's. Two Axle Suppliers.

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Dec 11, 2006
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North Carolina, USA
Just wanted to share some information I found out on my ’21 Silverado front and rear axles. Seem like for at least 2019 thru 2021 for GMC and Chevy half tons, there were two differential axle manufacturers. AAM (American Axle Manufacturing) and GM.

AAM axles were supplier A RPO SU4 front axle, RPO SU7 the rear.
GM axles were supplier B RPO SU5 front axle, RPO SU8 the rear.

These axles look different and the easiest way to identify, for me, was to look at the axels. The GM rear has the GM emblem stamped on the bottom of the differential housing. The front axle the same GM mark of excellence symbol stamped near the output shaft. It was very easy to locate these markings.

The AAM axles call for AC Delco 10-4091 (GM 19300457) 75W85; High Efficiency; Synthetic Hypoid Gear Oil. This a GL-5 oil.

The GM axles require AC Delco 10-4122 (GM 19368514) 75W85 Dexron Low Viscosity Gear oil. This is a GL-4 oil. A new formulation not like yester years GL-4.

Best I can tell this is accurate from my online research. I tow with this truck and wanted to find out before hand what gear oil I would need when I decide to change it and found out about the two different axel suppliers. In the grand scheme it may not make any difference as aftermarket gear oil suppliers seem to list only one oil for the models. However Rock Auto does show different AC Delco oils for each axle supplier. Hopefully this may help someone in a similar situation.
 
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Aug 20, 2003
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i'd like more info on the AC Delco 10-4122 (GM 19368514)
typically gl-4 isnt enough protection for hypoid gears... wonder how that fuel economy gear oil would perform over 120000 miles of towing etc.
Initial thought:
I think aftermarket gl-5 75w90 would be fine and deal with the .1mpg loss.
 

sohccammer427

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Dec 11, 2006
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452
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North Carolina, USA
i'd like more info on the AC Delco 10-4122 (GM 19368514)
typically gl-4 isnt enough protection for hypoid gears... wonder how that fuel economy gear oil would perform over 120000 miles of towing etc.
Initial thought:
I think aftermarket gl-5 75w90 would be fine and deal with the .1mpg loss.
  • GL-4 is suitable for hypoid gear service when they are under severe service but are without shock loading.
  • GL-5 is suitable for hypoid gear service under severe service and shock loads and not for use in a gearbox.

That kind of caught my attention too. The 10-4122 is listed as GL-4. But it's a new formulation. I don't know enough about differentials to know what type of shock loads they would incur. But I do agree a GL-5 in the GM axle would probably work fine. I forgot to mention in the OP that my truck did have the GM axles, both front and rear.
 

sohccammer427

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Joined
Dec 11, 2006
Messages
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North Carolina, USA
Here is some images of the axles in question. Like I stated earlier, if you crawl under and look the GM ones will be stamped with GM.
Under the diff on the rear, and looking from the driver side it's stamped on the side of the diff housing.


9.5" AAM rear:
9.5INCHAAM.thumb.jpg.dd208a09e9e9d2deb30fb31ccd0e7bde.jpg

9.5" GM rear:
9.5INCHGM.thumb.jpg.8b729718718c0ee056676b7f3a3bd882.jpg

AAM Front:
AAMFRONTAXLE.thumb.jpg.f51dc2f235f505a563ef4bc0c7267665.jpg





GM Front:

GMFRTAXLE.thumb.jpg.f8cf90cc8827c094ca24af7f07258e20.jpg
 
Joined
Jul 21, 2008
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Phila, PA
So... which one is the stronger, less troublesome, quieter? If one was buying a new truck, what one is the more desirable axle?
 

CKN

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Oct 14, 2014
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Utah
So... which one is the stronger, less troublesome, quieter? If one was buying a new truck, what one is the more desirable axle?
There have been almost very little issues with GM axles-up to this point.
 
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