GMC Sierra introduced all-new heavy-duty pickups during the ’07 model year. They were highlighted by all-new and differentiated exterior designs, two unique interiors and class-leading power and efficiency. They roll into 2008 ready for work or leisure, with minor refinements and enhancements, while still loaded with segment-leading and segment-exclusive features.
Sierra heavy-duties are offered in a range of 2500HD (three-quarter-ton) and 3500HD (one-ton) models and are available in WT, SLE and SLT trim. 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 2008 Sierra HD pickups offer many segment-best capabilities, including 18,500-pound (8,392 kg) gross combined vehicle weight rating for vehicles with a gas V-8 and a 13,000-pound (5,897 kg) conventional trailer weight rating enabled by a larger-capacity trailer hitch platform. Maximum towing capacity is 16,700 pounds (7,575 kg), when equipped with a fifth-wheel hitch.
2008 GMC Sierra HD
Changes to the Sierra 2500HD and 3500HD for ’08 are minor and include standard XM Satellite Radio on all models, availability of a power-adjustable driver’s seat on regular cab models with a bench seat and two new exterior colors: Dark Crimson Metallic and Sonoma Red Metallic.
Dually models in 2008 receive new, larger 17-inch wheels (replacing 16-inch wheels), which are available with bright wheel covers.
Bold and distinctive exterior designs
Sierra HD models have a distinctive front end with a prominent GMC emblem set in a large, chrome-ringed grille (black grille surround on Work Truck models). The grille is flanked by large, jeweled-appearance headlamps. 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 lamps that have a jeweled appearance. 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.
2008 GMC Sierra HD
Cab and cargo box configurations
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 such as 170-degree-opening (164 degrees with dual rear wheels) rear access doors with fully retractable power windows on extended cab models, 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 (1,718 L) with the regular box and 75.5 cubic feet (2,138 L) 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 new, 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.
2008 GMC Sierra HD
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 (227 kg).
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 (227 kg) 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.
Segment-leading interior designs with superior craftsmanship
GMC Sierra 2500HD and 3500HD are quieter, more spacious and refined inside, with increased passenger comfort and storage space. 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).
2008 GMC Sierra HD
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. Features on the premium interiors include power-adjustable heated bucket seats, leather-surface seats, leather-appointed steering wheel and selective chrome trim.
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 (90 mm) down and forward on the pure pickup interiors, while the premium interior instrument panel is located 5 inches (127 mm) 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 concealing 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.
2008 GMC Sierra HD
Additional highlights of GMC Sierra heavy-duty interiors include:
A stadium-style rear seat with a 60/40-split design and folding center armrest can be easily folded up to provide an uninterrupted load floor. Or, either section of the split seat can be stowed independently, allowing room for both cargo and a rear-seat passenger
A “double” glove box, which includes a large-capacity, traditional glove box and a new, covered storage compartment above it, with a 3.4-liter storage capacity
Models equipped with the luxury-inspired premium interior come with a single large glove box for substantial storage capacity
The premium interiors include large center consoles with the segment’s largest storage capacity: 20.1 liters of undivided volume
The pure pickup interiors feature a 6.1-liter armrest storage console and an underseat storage bin built into a new 40/20/40-split bench seat. This 9.1-liter lockable storage bin, which includes an accessory power outlet, is located under the center seat cushion and is large enough to store a laptop computer
The gauges have an analog display, with large, easy-to-read graphics. They are lit with ice-blue LED lighting, which provides crisp, bright illumination and a more upscale look. A driver information center is incorporated on the instrument panel
Air conditioning is standard on all models, with a dual-zone automatic system available on some models. The dual-zone system allows for up to a 30-degree F difference in temperature settings between the driver and front passengers
Power-operated rear side glass is featured on extended cab models. The windows lower completely into the rear access doors
Power-operated back glass is available on extended and crew cab models. The window operates with the touch of a button located on the overhead console.
A large, power-operated sunroof is available on extended and crew cab models. The crew cab sunroof has a tilt/slide design, with a sliding sun shade and express open/close feature. The extended cab sunroof uses a spoiler-type sunroof design that slides back over the roof surface
Ultrasonic Rear Parking Assist provides audible warnings of objects behind the vehicle
A heated windshield washer fluid system more effectively removes bug spatter and thin layers of ice and frost. When the system is activated, washer fluid is heated to 150 degrees F (60 C) or more
A diverse range of radio systems – including single-CD, six-disc CD, MP3- and DVD-capable – is available. Several radios feature RDS technology, which provides enhanced information for participating FM stations
A rear-seat entertainment system isavailable on crew cab models; it combines a dual-play radio system, rear-seat audio controls and a larger, eight-inch flip-down screen
Two touch-screen DVD-based navigation radio systems are offered; one is specific for systems equipped with the rear-seat entertainment system
The standard engine is a 6.0L gas V-8 with variable valve timing. It is rated at a best-in-class 353 horsepower (263 kW) and 373 lb.-ft. of torque (506 Nm)* on single rear-wheel configurations (up to 10,000 pounds gross vehicle weight rating). Variable valve timing helps improve performance and fuel economy.
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.
2008 GMC Sierra HD
A cleaner, more powerful Duramax 6.6L turbo-diesel engine is available. It continues to lead the segment in power and torque, with power ratings of 365 horsepower (272 kW) and 660 lb.-ft. of torque (895 Nm). Upgrades to the engine introduced in ’07 include a diesel particulate filter system that helps provide a 90-percent reduction in particulate matter and a 50-percent reduction in NOx (compared with pre-2007 standards), meeting a new federal government mandate that went into effect on Jan. 1, 2007.
The renowned Allison 1000 six-speed automatic transmission is partnered with the Duramax 6.6L turbo-diesel engine. It delivers good fuel economy, quietness and control. It features a class-first range selection function, which allows the driver to easily select the desired gears to match driving conditions, such as towing a trailer on a steep grade.
Chassis and driving experience
Working in concert with the powertrains are a strong chassis and responsive suspension systems. The vehicle frame is comprised of a sturdy ladder design that is reinforced with cross braces. It features a segmented design that enables easy and accurate adaptation of numerous lengths to accommodate the trucks’ five wheelbase lengths. The frame sections are joined with strong, overlapping segments that bolster overall strength and rigidity.
The strength of the frame and enhanced capabilities enabled by the powertrain systems allow the Sierra heavy-duty trucks to offer a larger, 2.5-inch trailer hitch receiver platform. This enables the trucks to pull a segment-leading maximum of 13,000 pounds (5,897 kg) with conventional trailers. Trucks with fifth-wheel hitches can tow up to 16,700 pounds (7,575 kg), when properly equipped.
2008 GMC Sierra HD
All 2500HD and 3500HD models ride on a wide, 68.6-inch (1,742 mm) front track. The rear track on 2500HD trucks is 66 inches (1,676 mm); the rear track on 3500HD models is 74.7 inches (1,897 mm), giving Sierra heavy-duty models a firmly planted feel.
Two suspension packages: Z85 and Z71. The Z85 suspension is standard on 2WD and 4WD models; the Z71 Off Road suspension is optional and includes additional chassis and suspension equipment, including skid plates.
A recirculating ball steering system delivers a confident feeling of control and on-center feel.
A high capacity, four-wheel disc brake system with Hydroboost and four-wheel ABS is standard on all models. The brake system includes large-diameter front and rear disc rotors and stiff brake calipers.
All heavy-duty models are available with an integrated trailer brake controller. It is integrated with the ABS system and provides immediate and measured brake force signaling to electric-controlled trailer brake systems. There is no requirement for external and/or aftermarket brake control systems. The brake controller switch is conveniently mounted on the lower-left section of the instrument panel.
Sierra heavy-duty models are designed to help drivers avoid crashes and protect passengers in the event one occurs. The robust ladder frame and strong body structure provide occupant protection. The frame is designed with crush zones that crumple to absorb crash energy, while the body structure incorporates the strategic use of high-strength steel and structural adhesives designed to help maintain passenger compartment integrity and manage energy in a crash.
Additional safety features include:
Frontal air bags are standard on all models
Segment-first front safety belt pretensioners with both front and rear crash sensing
A standard, high capacity four-wheel disc brake system with four-channel ABS system provides superior stopping capability
Ultrasonic Rear Parking Assist system is available and provides visual (LED lights) and audible warnings of objects behind the vehicle
Tire pressure monitoring system is standard on all models except Dually
Segment-exclusive factory-installed remote vehicle starting system is available on most models
Power-adjustable pedals complement increased front seat fore/aft travel to enable smaller-stature drivers to find an optimized driving position
2008 GMC Sierra HD
All retail models come standard with the OnStar Generation 7 system, including a one-year subscription to the Safe & Sound plan. The OnStar service includes the General Motors Advanced Automatic Crash Notification (AACN) system, making crash data available to emergency services to potentially dispatch the appropriate life-saving personnel and equipment to crash scenes faster. If the vehicle is in a crash that activates an air bag, the OnStar system automatically notifies an OnStar advisor, who will check on the occupants or summon emergency help if necessary. OnStar also can assist authorities in locating a vehicle if it is reported stolen and provides remote door-unlocking service (when the vehicle is equipped with power locks).