Designed for hauling heavy loads, Sierra heavy-duty trucks are offered in a range of extremely capable 2500HD (three-quarter-ton) and 3500HD (one-ton) models.

The 2009 Sierra HD lineup advances GMC's century of experience building nothing but trucks, exemplifying the brand's engineering excellence and delivering vehicles that customers can rely on for any task.

Sierra heavy-duty trucks are available in Work Truck, SLE and SLT trims. The range of configurations — three cab styles, three cargo box styles and five wheelbase lengths — delivers tremendous choice. Some full-size truck manufacturers do not even offer three-quarter-ton or one-ton heavy-duty trucks. And among those that do, the Sierra HD pickups offer many segment-best capabilities, including 18,500-pound gross combined vehicle weight rating for vehicles with a gas V-8 and a 13,000-pound conventional trailer weight rating enabled by a larger-capacity trailer hitch platform. Maximum towing capacity is 16,500 pounds, when equipped with a fifth-wheel hitch.

For 2009, changes to the Sierra 2500HD and 3500HD lineup include a number of safety-related and convenience features that bolster an already comfortable and refined driving experience.

They include:

Sierra HD models have a distinctive front end with a prominent GMC emblem set in a large, chrome-ringed grille. SLT models feature large foglamps set into the bumper, creating an upscale appearance that further reflects GMC's brand identity.

The trucks are refined looking, too, with doors that extend over the rockers for a smooth, uninterrupted look, and large headlamps. The door handles feature large, grab-style designs that are easy to open with gloves. Tolerances between panels are minimal — including a 50-percent reduction in the space between the cab and cargo box — which enhances the overall sleekness of the design.

Sierra 2500HD and 3500HD are offered in regular, extended and crew cab configurations, which are complemented with standard (6-foot 6-inch) and long (8-foot) cargo box lengths. Sierra 3500HD models also are available with the Dually dual rear wheel configuration on a long (8-foot) box. Features on extended models such as 170-degree-opening (164 degrees with dual rear wheels) rear access doors with fully retractable power windows offer increased versatility.

The pickup boxes have great versatility, strength and capacity. A one-piece wheelhouse and inner box side offers strength and a smoother, more integrated appearance. The boxes are 1.18 inches (30 mm) deeper in the front and 1.57 inches (40 mm) deeper at the rear than previous-generation models, with stronger inner walls that offer improved performance when fitted with ladder racks, toolboxes and other accessories. Cargo bed volume is 60.7 cubic feet with the standard box and 75.5 cubic feet with the long box.

Dually cargo boxes are completely made of steel, including hydroformed sheet metal outer fenders. They have a smooth, integrated appearance and enhanced strength. All Dually models feature marker lights on the fenders and sleek cab roof lights that are aerodynamically integrated into the top of the cab.

The tailgate designs include a lock and an available EZ Lift feature, with torque-rod assist. The tailgates are also easily removed by simply opening to 45 degrees and pulling straight out and away from the vehicle.

An innovative cargo management system is available and is complemented by a range of dealer-ordered accessory packages. Three rails that run the length of the box sides and the forward box wall are secured with high-strength anchors and, unlike competitors' systems, incorporate upper and lower tracks. Four adjustable tie-down brackets are included with each system and can be located anywhere on the tracks, each rated for a load point of 500 pounds.

At the heart of a comprehensive accessories portfolio for the pickups is a group of specific accessory products designed to integrate into the cargo management system. The rails enable the use of an overhead utility rack rated at 500 pounds loading capacity, a sliding diamond plate toolbox, a sliding bed divider and diamond plate side storage boxes. These accessories use either the upper or lower rails, allowing numerous combinations that can easily fit together or bypass one another as they slide along the rails. The toolboxes use a codeable lock, enabling the vehicle key to be used for locking and unlocking these accessories.

GMC Sierra 2500HD and 3500HD are quiet, spacious and refined inside. Each features two distinct interior designs that reflect their respective brand identities, including specific trim, appointments and gauge cluster appearance.

Base- and midlevel-trim models include a functional pure pickup interior design theme with a contemporary adaptation of GM's ergonomic cockpit instrument panel design. In addition, this interior includes specific door panels with large door pull and release handles, as well as unique seat configurations; center console and underseat storage systems. It also includes two glove boxes (a traditional lower glove box and a covered upper storage compartment).

Luxury-inspired premium interiors are standard on SLT models. They offer richly appointed features, including a distinct instrument panel design, large-capacity center console (20.1 L), specific door panels, seats and other trim elements. An SLT Convenience Package includes adjustable power pedals, universal home remote, locking EZ-Lift tailgate and rear parking assist.

Spaciousness in each interior trim level is enhanced with “low and forward” instrument panels that provide a more airy feel to the cabin as well as a panoramic field of vision. The instrument panels are mounted approximately 3.5 inches down and forward on the pure pickup interiors, while the premium interior instrument panel is located 5 inches down and forward. Both instrument panel designs are integrated into their specific door panels to create a swept appearance.

All interiors are refined and craftsmanship is highlighted by flush surfaces, tight gaps and tolerances on the instrument panel, center stack, clusters and other components. Most gaps on the instrument panels and clusters are 0.5 mm or less. Attention to detail was given to conceal fasteners and metal structural components of all seats.

There is no exposed hardware in the interior or doorsills. Soft-touch and low-gloss finishes for the instrument panels and other trim pieces are used throughout. The color and grain of the materials were carefully selected to provide a premium look.

Complementing the interiors' finely crafted look and feel is exceptional quietness. All trim levels — even base work truck models — benefit from a comprehensive system that delivers a passenger environment almost devoid of noise.

This is achieved with the use of strategically placed sound-deadening and sound-absorbing material in the body structure — including liquid-applied dampener on the floor and front-of-dash — as well as the inherent, vibration-minimizing traits of the stiffer frame and quieter attributes of the aerodynamically tuned exterior. Also, improved-design door sealing and a doors-over-rockers design help eliminate road and wind noise.

The standard engine is a 6.0L gas V-8 with variable valve timing. It is rated at a best-in-class 360 horsepower and 380 lb.-ft. of torque on single rear-wheel configurations (up to 10,000 pounds gross vehicle weight rating). Variable valve timing helps improve performance and fuel economy.

For models with a gross vehicle weight rating greater than 10,000 pounds, the 6.0L engine is rated at 322 horsepower and 380 lb.-ft.

A Hydra-Matic 6L90 six-speed automatic transmission is paired with the engine. This powertrain combination offers a higher maximum gross combined weight rating (GCWR) — 18,500 pounds (8,392 kg) — than previous gas-powered combinations and is the segment leader for vehicles with a V-8 gas engine.

The 6L90 has a wide, 6.04:1 overall ratio — including two overdrive gears — that helps deliver an excellent balance of performance and fuel economy. It also offers manual range selection and tap up/tap down control.