BRANSON, Mo. — 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 new structure that’s modular in design to allow multiple configurations for cabin size and box length, bulge from new sheetmetal styling and ripple with enthused strength due to a new series of powertrains that muscle up to the head of the heavy class in terms of raw horsepower, engine torque and efficiency for towing and toting hefty loads. They also provide uncommonly comfortable passenger compartments in cabs equipped with two or four doors, and can perform tricks rarely seen among work trucks: They’re smooth in suspension ride and downright easy to operate. We proved the point during a driving tour through the Ozark Mountains of Missouri while cycling through a variety of Silverados that included the 2500HD three-quarter-ton and one-ton 3500HD series trucks outfitted with cab dimensions of regular and extended lengths plus a four-door Crew Cab, two traction systems in two-wheel-drive and four-wheel-drive, and all three of the humongous new engines.

The Regular Cab Silverado brings a bench seat for three and two front-hinged doors with a truck box in back of short (78.7 inches) and long (97.6 inches) lengths, or the Chassis Cab with no box aboard for customizing the rear by installing specialized equipment like a snowplow or hoist.

Rear doors for the Extended Cab are hinged on the rear edges. They close by tucking behind the front doors and open in the absence of B-pillars toprovide a broad and unencumbered space for easy entry to both the front bench seat or a rear three-person jump seat.

For the Crew Cab, with full-size rear area and full-size bench seat for three, the conventional front-hinged back doors work like front doors in an arrangement that emulates a four-door sedan.

A surprising favorite combination encountered during our tests in the Ozarks proved to be an unlikely configuration: It was a four-wheel-drive 3500HD Dually (with dual wheel sets on the rear axle to carry massive loads) in Chassis Cab format and the back platform rigged with a wrecker’s hoist for commercial towing duty.

Up front, this Chevy packed a new 6.6-liter V6 turbo-diesel engine that delivered 300 hp at 3100 rpm and enormous torque figures up to 520 lb-ft at 1800 rpm.

It stood tall and stretched long, with step rails below doors and handles on pillars to help hoist yourself aboard.

In the extended cab trimmed in deluxe SLT edition, the high-back front bucket seats were covered in leather and moved in six directions through power controls. Luxury components ranged from power windows and electric exterior mirrors to a tilting steering wheel, cruise control, air conditioning and a nice audio system.

In effect, that big wrecker truck packed 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 else on the road, this particular Silverado HD reminded us of some steroidal body builder scrubbed and polished, then dressed up in black tie and tuxedo.

But Chevy’s work trucks don’t all have to be fancy. With three trim choices and as many as 32 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.

All aspects of the new design for these Silverado HD trucks trace to a revamped structural system that first appeared two years ago with the Silverado half-ton light-duty trucks.

The structure utilizes an innovative modular frame with hydroformed front sections designed to increase the strength and rigidity of the frame, as well as aid the assembly process by eliminating hundreds of weld points, then reduce squeaks and frame vibrations due to the good fit with suspension elements.

Compared to Chevy’s previous heavy duty trucks, these new ones show front and rear track widths expanded by four to five inches to form a broad and stable platform, with the chassis holding as high as 8.9 inches for ground clearance.

The revised suspension system includes independent front long-and-short arm arrangement with torsion bars used as springs. In back, semi-elliptical multi-leaf springs deploy in two stages for the 2500HD trucks and in three stages for 3500HD one-ton models.

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.

Standard safety elements range from dual frontal air bags to seat-mounted three-point safety belts, child security locks for rear doors and daytime running lamps, with some trim levels also listing as standard equipment the OnStar communication and assistance system for in-vehicle security and information services.

Despite so many changes regarding structure, styling, handling and comfort, all improvements become secondary considerations to the new lineup of powerhouse engines and strong transmissions developed for these trucks.

There are two gasoline-powered Vortec V8 choices plus the Duramax turbo-diesel V8.

The Vortec 6000 6.0-liter V8 serves as the entry plant and produces more power and torque than any other standard engine in this class. Output rises to 300 hp at 4400 rpm, with torque skewed to 360 lb-ft at 4000 rpm.

It couples to a five-speed manual transmission or the GM Hydramatic 4L80-E four-speed automatic.

A new Vortec 8100 8.1-liter big-block V8 is optional with 340 hp at 4200 rpm and 455 lb-ft of torque at 3200 rpm. It works with either a ZF six-speed manual or an impressive Allison 100 five-speed automatic.

The Duramax 6600 6.6-liter V8 direct-injection turbo-diesel puts out the king-of-the-road power and torque ratings, and it too mates with the ZF six-speed manual or Allison five-speed automatic.

Thanks to all that beef, the Silverado HD now boasts the highest gross vehicle weight (GVW) ratings that run to 9200 pounds for the three-quarter-ton 2500HD and up to 12000 pounds for the one-ton 3500HD series with four-wheel-drive and either the Vortec 8100 gas V8 or Duramax 6600 diesel.

2001 CHEVROLET SILVERADO HEAVY DUTY TRUCKS

Description………………Full-size super-strength truck

Model options…………….2500HD three-quarter-ton
3500HD one-ton

Trim options……………..SL / SLE / SLT

Configurations……………2-door Reg. Cab Long Box
2-door Reg. Cab Chassis
4-door Ext. Cab Short Box
4-door Ext. Cab Long Box
4-door Ext. Cab Chassis
4-door Crew Cab Short Box
4-door Crew Cab Long Box
4-door Crew Cab Chassis

Wheelbase………………..133.0 inches
137.0 inches
143.5 inches
153.0 inches
157.5 inches
161.5 inches
167.0 inches

Overall length……………222.1 inches
225.0 inches
227.7 inches
237.3 inches
246.6 inches
246.7 inches
249.5 inches
256.2 inches
273.5 inches

Engine size………………OHV 6.0-L V8
OHV 8.1-L V8
OHV 6.6-L V8 TD

Transmissions/speeds………6.0-L: Manual/5, Auto/4
8.1-L: Manual/6, Auto/5
6.6-L: Manual/6, Auto/5

Rear/front drive………….Rear 2WD, 4WD

Steering…………………Power recirc. ball

Braking………………….Power 4-disc/ABS

Air bags…………………2 (front)

Maximum GVWR……………..2500HD: 9200 pounds
3500HD: 11400 pounds
Chassis: 12000 pounds

Maximum trailer towing…….12000 pounds