If you’re driving a late-model GM or Dodge heavy-duty truck, then chances are you have a big rearend. Now don’t take that as an insult. We’re talking rear axles here. Those found under the 3⁄4- and 1-ton GM and Ram trucks are made by American Axle Manufacturing. These trucks have three different rear axles based on ring gear diameter: the Dodge 101⁄2-inch, the GM 101⁄2-inch found in gas 3⁄4-tons, and the 111⁄2-inch found in both manufacturers’ diesel and 1-ton trucks. These three axles are all massive and ideal for large tires in the 37- to 44-inch range. They come with disc brakes, and are all full-floaters, but with this size come weight and ground clearance issues. We have been noticing a trend of aftermarket axle companies developing larger axles for the off-road market, but we’ll delve into that in the future. For now we’ll give you some insight on why you might (or might not) want an AAM axle under your next 4x4 project. The Dodge Ram 101⁄2-inch rear axle is most often found under the Hemi gas-powered Dodge 3⁄4-ton trucks starting with the ’03 model. You will also find this axle under the new Dodge Power Wagon trucks equipped with 4.56 gears and selectable electric lockers. These axles have minimal aftermarket support in the way of locking differentials, and gearing is only available from 3.73 down to 4.56.The Dodge Ram 101⁄2-inch rear axle is most often found under the Hemi gas-powered Dodge 3⁄ The GM version of the AAM 101⁄2 (foreground) in use since 2001 is just a new version of the tried and true Corporate 14-bolt (background). Parts from the GM to Dodge 101⁄2 do not interchange, though parts from the old 14-bolt do interchange with the new AAM 14-bolt. The center section is finned for added cooling and retains the removable pinion support and three-pinion bearings as compared to the Dodge’s two. Gearing and locker selections for the AAM 14-bolt axles are abundant.The GM version of the AAM 101⁄2 (foreground) in use since 2001 is just a new version of th The GM and Dodge version of the AAM 111⁄2 is very similar, using the same ring gear and carriers, but they are not 100-percent interchangeable due to suspension mounting brackets and axleshaft lengths. The AAM 111⁄2 is a massive rearend and often overkill for a trail rig, unless you are running huge power or giant tires to deal with the low ground clearance.The GM and Dodge version of the AAM 111⁄2 is very similar, using the same ring gear and ca We took a Dodge 3500 with the 111⁄2 AAM rear axle to Pacific Fabrication to swap out the AAM limited slip for a more positive ARB Air Locker and found the conversion fairly painless. One aspect of the AAM axles we appreciate is the reusable diff cover gasket, which makes inspection, repair, or modification to the rearend one step easier.We took a Dodge 3500 with the 111⁄2 AAM rear axle to Pacific Fabrication to swap out the A Before changing a ring-and-pinion or differential, it is good practice to run a pattern and check backlash on the old gears in an axle. The side bearing adjusters on all the AAM 3⁄4- and 1-ton axles make setting up these axles straightforward.Before changing a ring-and-pinion or differential, it is good practice to run a pattern an We did not change the gear ratio in this AAM 111⁄2 axle, but we did need to swap the ring gear and the tone ring over from the factory differential to the Air Locker. The tone ring is part of the speedometer and ABS/traction system.We did not change the gear ratio in this AAM 111⁄2 axle, but we did need to swap the ring We also opted for a new bearing installation kit from Randy’s Ring & Pinion featuring new Timken bearings. The bearings support the differential and pinion and must be tight but not overtight for proper gear mesh without wear.We also opted for a new bearing installation kit from Randy’s Ring & Pinion featuring new The ARB Air Locker is activated by air pressure and needs a hole drilled in the axlehousing and copper line plumbed to an outside plastic line that runs to the air compressor. We feel it is only a matter of time before Dodge and GM offers a factory selectable locker in their diesels to compete with those found in the current Ford Super Duty.The ARB Air Locker is activated by air pressure and needs a hole drilled in the axlehousin After assembly simply reinstall the 11⁄2-inch, 30-spline, full-floating axleshafts. This is the same diameter and spline on all these AAM full-float axles, though lengths differ.After assembly simply reinstall the 11⁄2-inch, 30-spline, full-floating axleshafts. This i We also installed a new Grizzly locker and a set of 4.88 gears from Yukon in a Dodge 111⁄2 dualie rear axle at home. Though changing the differential alone isn’t difficult, changing gears in this axle is a larger task simply due to the massive size of the axle. You’ll need a hydraulic press and a large bearing puller to remove the old pinion bearings. You may also want an engine hoist just to move the housing.We also installed a new Grizzly locker and a set of 4.88 gears from Yukon in a Dodge 111⁄2 Unlike a 14-bolt Detroit Locker that is installed in a factory open carrier, the Grizzly 111⁄2 is a complete carrier and replaces the factory limited slip or open carrier. Torquing the ring gear bolts and bearing caps requires up to 207 lb-ft (175 for ring gear bolts) and a way to hold the carrier firm while tightening.Unlike a 14-bolt Detroit Locker that is installed in a factory open carrier, the Grizzly 1 One of the most challenging parts of the assembly is crushing the crush sleeve for prescribed pinion bearing preload. We used a 3⁄4-inch impact wrench and hammered away at the pinion nut with a chain attached to the pinion flange until we reach the require 25 to 30 in-lb of preload.One of the most challenging parts of the assembly is crushing the crush sleeve for prescri Finding a quality diff cover for the GM AAM 101⁄2 isn’t hard, but finding a steel version for the Dodge 101⁄2 or 111⁄2 is. This steel 111⁄2 diff cover is made by DT Products.Finding a quality diff cover for the GM AAM 101⁄2 isn’t hard, but finding a steel version We also like the Aluminum factory diff cover offered on the Ram trucks with the Max-Tow package, which is available through Mopar.We also like the Aluminum factory diff cover offered on the Ram trucks with the Max-Tow pa SOURCES DT Products 484 EZ St. Prescott AZ 86301 Yukon Axle and Gear 8-88/-231-2417 yukongear.com American Axle & Manufacturing Mopar P.O. Box 21-8004 Auburn Hills MI 48321 800-992-1997 www.mopar.com Pacific Fabrication 235 Tennant Ave. Unit 2 Morgan Hill CA 95037 408-250-1772 www.pacificfab.net Randys Ring & Pinion ARB 4x4 Products 720 SW 34th Street Renton WA 98057 800-761-8192 http://www.arbusa.com By Fred Williams Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!