The '99-to-present GMC and Chevy 3/4-ton trucks are two of the most popular fullsizes ever to spring from the General Motors lineup. While the trucks' peppy Duramax diesel engines and bulletproof Allison transmissions really get them moving, the low factory ride height can sometimes blur the line between a heavy-duty truck and an overgrown car. With the aftermarket full of suspension kits for the 3/4-ton HDs, it can be a little over-whelming to narrow your lift options down to one. For us, the price, quality of parts, and ease of installation are major factors when looking into a suspension kit. So when the time came to give our '04 Chevy 2500 HD 4x4 a little boost, we set our sights on the new 6-inch suspension system from Pro Comp.
The completely redesigned '99-'09 GM 3/4-ton 6-inch kit nets the latest technology in IFS suspension lifts. The new knuckle-style kit allows the installer to lift the truck without relocating the upper control arm and provides a minimal front track-width increase.
Among the kit's highlights is its complete compatibility for late model GMs equipped with StabiliTrack. This means no annoying dash lights or beeping from the truck's taller stance.
To install the Pro Comp 6-inch we went to the pros at 4Wheel Parts in Thousand Oaks, California. With all our parts waiting for us at the store, we rolled in with a bone-stock '04 Chevy 2500 in the a.m., and by day's end we had our HD lifted, aligned, and ready to hit the town and the trail.
 1. To clear the new subframe...  1. To clear the new subframe assembly, we trimmed out a small section of the original IFS support. To beef up the independent front section, Pro Comp provides a weld-in plate to strengthen the modified factory member. |  2. With the front differential's...  2. With the front differential's upper mounting tab removed, we bolted on the differential relocation bracket. Securing the diff between the two Pro Comp suspension members, we were able to bolt our factory front driveshaft back in place. |  3. The heart of the new 6-inch...  3. The heart of the new 6-inch kit is the new knuckles, which are designed to raise the front of the Chevy without increasing the track-width tremendously. This knuckle-style suspension system cuts down install time by retaining the upper control arms in their factory locations. |
 4. After drilling a few holes...  4. After drilling a few holes in the 3/4-ton's frame, we mounted up the CNC-cut, powdercoated torsion bar drop brackets and subframe assembly support links. The torsion bar keys and bars were then installed, but left to be adjusted until we placed the truck on the 4Wheel Parts four-wheel alignment rack. |  5. A mild block, U-bolts,...  5. A mild block, U-bolts, and bumpstop spacers comprise the rear suspension lift and bolt together in no time flat. To help keep the ride smooth, a Pro Comp MX-6 adjustable shock was outfitted at each corner of the truck, giving the operator the ability to fine-tune the ride. |  6. For tires and wheels we...  6. For tires and wheels we went with a 35x12.50 Pro Comp Xtereme All Terrain mounted on a set of 18x8.5 Pro Comp 28 Series wheels. With the All Terrain's E-range sidewall, tri-ply construction, and mild tread stagger, they were a great fit for the Duramax-powered Chevy that's used as a daily driver, light wheeler, and tow rig. |
Ride & Drive
The on-road handing and ride quality of the HD is smooth, and tire noise is practically nonexistent. Off highway the truck performs well and works excellently for cruising around the desert or hauling the off-road toys over the terra. Overall, we like the fresh look and feel of the bigger bow-tire. The ride height of the quad cab is tall enough to give the truck an impressive stance, but still low enough to retain its function as a workhorse and daily driver.