Four Wheeler Magazine upgrades 2002 GM rear end with Ram-Air diff cover

Jason Gonderman decided it was time to upgrade Four Wheeler Magazine’s 2002 2500HD’s tires to 37s. This would effectively raise the gear ratio (numerically lower) by about 20%. After the tires, it would be as if he’d installed 3.23:1 axle gears. The result would be more difficult acceleration but lower engine rpm at highway speeds.

To get the engine back in its proper powerband and regain the lost acceleration, he opted to change the axle gears to a lower (numerically higher) gearset. To get the truck back to relative normal, he would have needed to install 4.30:1 gears. However, because he did a six-speed transmission conversion, and to get a bit of added performance, he opted to go even lower to 4.56:1 gears.

In addition to the new Yukon Gear set, Jason also ordered up a master install kit, the company’s Dura Grip limited-slip differential, and 4340 chromoly axle shafts.

With all that time and effort into new gears, Jason opted to keep the new rear end as cool as possible with the new Banks Ram-Air rear differential cover and fresh AMSOIL 75W90 Severe Gear oil and AMSOIL Slip Lock.

See the full installation at