Chevrolet Silverado HD — Heavy Duty — signifies big trucks

2007, Chevrolet, Silverado HD

COLUMBIA FALLS, Mont. -- Heavy Duty: That's the tell-all descriptive for a new series of big and powerful work trucks developed by General Motors for the upward expansion of Chevrolet's full-size line of Silverado pickups.

These behemoth trucks, built on a strong structure that's modular in design to allow multiple configurations for cabin size and box length, bulge from new chiseled sheetmetal styling and ripple with enthused strength due to revamped gas and diesel engines teamed with efficient six-speed automatic transmissions to deliver tall power and torque ratings for toting and towing hefty loads.

On a hilly course in the Rocky Mountains of Montana, a big trailer -- packed with weight equal to a pair of big draft horses -- trails behind our workhorse Chevy truck, new Silverado HD (Heavy Duty) for the one-ton 3500HD series with four-wheel-drive (4WD) in four-door Crew Cab configuration containing front bucket seats and a rear bench sized for three broad-shouldered adults, plus a long-box bed in back stretching for eight feet.

Beneath the high-hitched front hood, this 3500HD truck carries an optional Duramax 6.6-liter V8 direct-injection turbo-diesel engine which musters a horsepower rating at the top of the class.

The diesel plant links to a remarkable Allison 1000 six-speed electronic automatic transmission. A sophisticated transmission control module in the transmission acts to select gears and engage the torque converter lockup.

For towing a trailer like the one trailing behind our rig, this intelligent transmission in Tow-Haul mode stabilizes shifting by automatically selecting an ideal gear after sampling various factors, such as engine speed and throttle position.

On long downhill grades over U.S. 2 highway in the Rockies, the transmission control module actually downshifts without driver prompting -- from sixth gear down to fifth, then down further to fourth or third as needed.

It drops to lower gears to retard the weighty truck-trailer rig on a downhill slope and spare the big disc brakes from overheating.

In effect, the transmission package erases all traces of effort related to the chore of driving this trailer-toting truck. All we as the driver need to do is grip the steering wheel and keep the prow pointed in the proper lane.

Reducing the driver's workload becomes an apparent theme with the new designs for Silverado HD trucks.

In the stretched cab of a deluxe LTZ edition, the high-back front bucket seats are clad in leather and moves in multiple directions through power controls. Luxury components range from power windows and electric exterior mirrors to a tilting steering wheel, cruise control, air conditioning and nice audio gear.

In effect, the big truck packs all of refinements of a premium luxury car.

With so much heavy duty work gear aboard and that monster diesel capable of out-pulling and out-powering anything on the road, this particular Silverado HD reminds us of some steroidal body builder scrubbed and polished, then dressed up in a tuxedo.

But Chevy's HD work trucks don't all have to be fancy.

With three trim choices and so many different configurations for cab and bed and powertrain and traction, the series consists of a complex array of models that can be bare and simple at one extreme or refined and luxurious for the other.

The series includes 2500HD three-quarter-ton and one-ton 3500HD trucks with cab dimensions of regular and extended lengths plus the Crew Cab, two traction systems in rear-wheel two-wheel-drive (2WD) or 4WD format, two lengths for the truck box and choices for a gasoline-driven V8 engine or that Duramax turbo-diesel.

GM's Vortec 6000 6.0-liter V8 serves as the gasoline-swigging plant. Output rises to 353 hp at 5400 rpm, with torque skewed to 373 lb-ft at 4400 rpm.

This engine ties to the GM Hydra-Matic 6L90 transmission with six forward gears.

The Duramax 6.6-liter V8 turbo-diesel engine generates 365 hp at 3200 rpm and torque of 365 lb-ft at 1600 rpm.

* There are three different cab styles -- Regular Cab (two doors and a bench or buckets), Extended Cab (bench or buckets in front of a back bench with two wide-swing access doors tucked behind the two front doors), and Crew Cab (a spacious four-door cab with front buckets or bench and a big back bench for three).

* There are two different lengths for the rear truck bed -- Standard Box (78.7 inches) and Long Box (97.6 inches). Each version features two-tier loading with pockets stamped into inner side panels to accept 2x8 planks stretched across the width of the box, as well as built-in bulkhead dividers. And the EZ Lift tailgate employs a gas-charged damping strut for a smooth drop on opening and easy lift for closing.

* There are two different suspension packages -- a Z85 suspension that's standard on 2WD and 4WD models and the Z71 off-road kit which includes additional chassis and suspension equipment plus underbody skid plates.

Steering, with power assistance in the integral recirculating ball device, has been tuned to produce better control with improved on-center feel and crisp swing action.

Brakes to rein so much tonnage with such powerful engines by necessity must be big and strong. The GM design installs four big discs with hydro-boost power control and the link to a computerized anti-lock system (ABS).

Optional is a new factory-installed trailer brake controller integrated with the ABS. It helps to stabilize a tow rig during emergency stop maneuvers.

The on/off switch for the trailer brake controller is located in the instrument panel.

And Chevy's HD trucks maximize towing capacity by upgrading the tow hitch platform with a 2.5-inch receiver, which permits a higher-capacity tow hitch. The hitch platform attaches directly to the truck's frame.

Maximum conventional trailer tow weight for Silverado HD trucks rises to 13000 pounds

Standard safety elements for the trucks range from dual frontal air bags to three-point safety belts, child security locks for rear doors and daytime running lamps, with standard equipment including the OnStar communication and assistance system for in-vehicle security and information services.

Chevrolet offers Silverado HD trucks (2500HD and 3500HD) in a broad range of prices -- with MSRP figures stretching from $23,675 to $39,888.

By Bob Plunkett

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Images of the 2007, Chevrolet Silverado HD

2007 Chevrolet Silverado front view
2007 Chevrolet Silverado front view
2007 Chevrolet Silverado interior shot
2007 Chevrolet Silverado interior shot
2007 Chevrolet Silverado dash
2007 Chevrolet Silverado dash
2007 Chevrolet Silverado rear perspective
2007 Chevrolet Silverado rear perspective