’06-’07 Chevrolet Silverado 2500 HD
Price Range: $14,000 to $23,000 Mileage Range: 70,000 to 180,000 miles
There is a lot to like about the classic–body style Chevy HDS. For starters, they boast powerful V-8s in the form of the 6.6L Duramax diesel or the optional 8.1L big-block gasser—both of which pack 300 hp or better. Backing up these potent engines, you have a choice between the Allison 1000 transmission— plucked right out of the medium-duty segment—or the trusty ZF-6 manual. In addition to that, you get the largest axle ever offered on a single-rearwheel pickup, the AAM 1150, and the plushest ride of any 3⁄4-ton truck thanks to the independent front suspension.
Saving the best for last, the final two years of production represent GM’S finest hour with the GMT800 platform. By the time the ’06 model HDS came along, the fuel system and overheating quirks found in the Duramax-powered ’01-’05 trucks had been solved and the latest diesel engine, the LBZ, embodied the most tried-and-true version of the 6.6L ever assembled. On top of its class-leading 360 hp, the LBZ turned out 650 lb-ft of torque at just 1,600 rpm. Add in the fact that the Allison 1000 gained double overdrive in the form of a 0.61:1 ratio sixth gear, and you had a powertrain that was virtually incapable of breaking a sweat with a trailer in tow—and a truck that could achieve 18-21 mpg empty.
-> As we stated, the AAM 1150 is the largest axle ever employed in a North American single-rear-wheel pickup—and it’s pretty darn tough. It features an 11.5-inch-diameter ring gear (hence 1150), 1.5-inchdiameter axleshafts, full-floating wheel hubs, and a 14-bolt differential cover. Its one Achilles’ heel is the factory Gov-loc limited slip that’s prone to failure when added horsepower and/or larger wheels and tires are combined with aggressive off-road driving.
<- At a time when Ford had yet to release the Torqshift automatic and Dodge’s Torqueflite A727based four-speeds were dropping like flies, GM dug into the medium-duty parts bin and pulled out a major trump card in 2001: the Allison LCT 1000. The heavy-duty slushbox gained a sixth gear (double overdrive) for the ’06 model year, and thanks to GM’S inclusion of a Tapshifter along the shift column, customers had full control over its shift points.
<- Learning from the injector failures and overheating issues associated with the LB7 (’01-’04) and LLY (’04.5-’05) engines, GM’S LBZ Duramax features a host of improvements over its predecessors. A less restrictive intake path to the turbo is employed, a larger radiator is used, and the Bosch common-rail injection system’s peak pressure checks in at 26,000 psi (versus 23,000 psi on earlier engines). As a result, the ’06-’07 HDS are more reliable and make substantially more power than their forefathers did.