When it comes to utility, there’s not much in the private sector that can beat a crew cab four-wheel-drive dualie. They can seat an army, tow a house, have enough payload capacity to fill the bed with a midsize sedan, and—even in stock form—have a look that makes the saltiest farmer’s heart melt. But as good as these trucks are in factory trim, there is always room for improvement.
01: To kick the project off in the right direction, we headed down to the 4Wheel Parts store in Redondo Beach, California, where expert technician Adolfo Eudave set to work swapping in a set of 4.10:1 G2 gears for our Chevy HD. With plans to add 37-inch tires in the near future, this gear change will ensure our engine remains comfortably within its power band once the larger rubber is installed.
02: The rear of our dualie sports a full-floating AAM 1150 “14-bolt” axle. Behind the cover, we find an 11.5-inch, 3.73:1 ring gear and GM Gov-Loc differential.
03: Removing the outer rear wheel was necessary to access the wheel hubs. The axleshaft retaining bolts were then removed, allowing the unit to slide out of the differential. It’s not necessary to completely remove the shaft to gain access to the differential.
04: Eudave then marked each of the differential bearing caps to facilitate proper reinstallation, and then proceeded to remove the retaining bolts, freeing the differential from the housing.
05: With the differential, pinion gear, and bearing races removed, the housing was cleaned up and ready to receive the fresh ring and pinion set.
06: Reassembly started with Eudave installing the pinion bearing races with his specially designed race driver. The races need to be driven in with equal pressure around the entire face to ensure a proper seat.
07: Next, fresh Timken bearings were pressed onto the new pinion, along with a set of new carrier bearings on the differential.
08: Once the bearings were installed, the new G2 ring gear was bolted onto the Gov-Loc differential. Red Loctite was applied to all the bolts before being driven in and torqued to spec.
09: Setting the backlash on the AAM 1150 axle is quite easy. Using a small pick, Eudave set an initial backlash adjustment for the new ring and pinion by turning the differential adjuster nuts built into the housing.
10: Thanks to his years of experience, Eudave was able to get a perfect gear mesh with minimal adjustment.
11: A G2 aluminum differential cover wrapped up the rear end. Giving a mean look, these covers are high-strength heat-treated aluminum, built to withstand direct hits. They also feature a fill plug with an integrated dipstick, drain plug for mess-free oil changes, and a fully machined seal surface for a leak-free installation.
12: Moving to the front, Eudave first removed the front skidplate and then the outer halfshafts. The differential was then removed from the truck and placed on the bench to be cracked open.
13: Following the same procedure as the rear, Eudave replaced the factory ring and pinion gears with 4.10:1 G2 units. Fresh Timken bearings and races were installed and the gears were fitted back into the housing.
14: With the case split, you get a good look at how the differential is oriented. The 9.25-inch ring gear and high-mounted pinion are a tight fit inside the aluminum IFS housing.
15: Wrapping up the install, the front differential case halves were mated back together, and the entire unit was reinstalled in the front of the truck in the reverse order of how it came out.