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AAM 11.50 Rear Differential

AAM 11.50 inch Axle/Differential Specs & Information

The AAM 11.50 inch is a full floating, heavy duty differential found in GM, Dodge, and Ram Trucks applications. Beginning in 2001, GM replaced its popular 14 bolt rear differential in 3/4 and 1 ton pickups with the AAM 11.50. The AAM's 11.5 inch ring gear is significantly larger than the 14 bolts 10.5 inch ring gear, and the gross axle weight rating of the AAM model is approximately 1,500 lbs greater. Dodge began using the AAM 11.50 in its Ram 2500 and 3500 models for the 2003 model year, which coincided with a major redesign of these models. The axle was used in both single and dual rear wheel ("duallie") applications.

Although similar internally, GM and Dodge/Ram versions of the axle assembly are not interchangeable due to differences in the axle tubes, hubs, and brake/suspension mounting bracketry, although both use 30 spline axle shafts. Early GM units (until the 2014 model year) relied on a paper differential cover gasket while later GM and all Dodge/Ram assemblies employ a reusable rubber gasket, prompting simplified maintenance. ACDelco 23445892 is cross compatible across both variations for all model years and replaces the early GM paper gaskets. The 2014+ AAM axle for Ram applications features provisions for the Ram 2500/3500 rear coil spring suspension system and thus is not cross compatible with any of the leaf spring applications.

AAM 11.50 Differential Specs

Manufacturer American Axle & Manufacturing
Years Produced 2001 - 2019
Applications 2001 - 2019 Chevrolet Silverado/GMC Sierra 2500HD, 3500HD
2003 - 2009 Dodge Ram 2500, 3500
2010 - 2019 Ram Trucks Ram 2500, 3500
Housing Material Cast iron
Differential Type Full floating rear differential
Ring Gear Diameter 11.50 in
Axle Spline Count 30 spline
GAWR ~10,000 lbs (GM rates @ max 9,375 lbs, Ram rates @ max 9,750 lbs)
Ratios GM Applications 3.73 : 1, 4.10 : 1, 4.63 : 1
Dodge/Ram Applications: 3.42 : 1, 3.73 : 1, 4.10 : 1
Carrier Break(s) None
Drain Plug Torque 34 - 54 ft-lbs (25 - 40 N-m)
Fill Plug Torque 34 - 54 ft-lbs (25 - 40 N-m)
Differential Cover Bolt Torque 43 - 62 ft-lbs (32 - 46 N-m)
Differential Cover Gasket[1] ACDelco 23445892
Lube Oil Spec[2] GM Applications SAE 75W-90 full synthetic gear oil
Dodge/Ram Applications: SAE 75W-90 full synthetic
75W-140 full synthetic gear oil
Lube Oil Capacity[3] 3.8 - 4.2 U.S. quarts
Identification 14 bolts securing differential housing to cover
AAM 11.50 differential cover bolt pattern

[1] - Although ACDelco is GM's service brand, this reusable differential cover is cross compatible with all Dodge/Ram Trucks applications.
[2] - Dodge/Ram applications recommend a 75W-140 gear oil for heavy towing applications; a full synthetic gear oil must be used in any case.
[3] - Oil capacity is nominal; always fill differential housing to bottom of fill plug with vehicle parked on level ground.

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Source(s)
American Axle & Manufacturing
General Motors; 2001 - 2019 GMC Sierra/Chevrolet Silverado owners manuals
Dodge/Ram Trucks; 2003 - 2019 Ram 2500/3500 owners manuals