The GMC Sierra 3500HD III, produced from 2007 to 2010, represented the third generation of the Sierra 3500 heavy-duty pickup truck. This generation, designated GMT900, offered a significant redesign compared to its predecessor, focusing on increased capability, improved interior refinement, and enhanced safety features. The Regular Cab Long Box configuration, paired with the 6.0-liter Vortec LY6 V8 engine producing 360 horsepower and a four-wheel drive (4WD) system, was a popular choice for buyers needing a robust work truck. This particular variant occupied a middle ground in the Sierra 3500HD lineup, offering a balance between capability and affordability, positioned below the more powerful Duramax diesel options and above the base work truck trims.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD III (GMT900) Regular Cab Long Box |
| Type (Engine) | 6.0 V8 (360 Hp) 4WD SRW Automatic |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 2 |
| Doors | 2 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 7.2 kg/Hp, 138.3 Hp/tonne |
| Weight-to-torque ratio | 5.1 kg/Nm, 197.8 Nm/tonne |
| Power | 360 Hp @ 5400 rpm |
| Power per litre | 60.3 Hp/l |
| Torque | 515 Nm @ 4200 rpm, 379.84 lb.-ft. @ 4200 rpm |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Vortec LY6 |
| Engine displacement | 5967 cm3, 364.13 cu. in. |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 101.6 mm, 4 in. |
| Piston Stroke | 92 mm, 3.62 in. |
| Compression ratio | 9.6:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV |
| Engine oil capacity | 5.7 l, 6.02 US qt | 5.02 UK qt |
| Coolant | 15.5 l, 16.38 US qt | 13.64 UK qt |
| Kerb Weight | 2603 kg, 5738.63 lbs. |
| Max. weight | 4490 kg, 9898.76 lbs. |
| Max load | 1887 kg, 4160.12 lbs. |
| Trunk (boot) space – maximum | 2170 l, 76.63 cu. ft. |
| Fuel tank capacity | 129 l, 34.08 US gal | 28.38 UK gal |
| Permitted trailer load with brakes (12%) | 5670 kg, 12500.21 lbs. |
| Length | 5714 mm, 224.96 in. |
| Width including mirrors | 2436 mm, 95.91 in. |
| Height | 1919 mm, 75.55 in. |
| Wheelbase | 3378 mm, 132.99 in. |
| Front track | 1742 mm, 68.58 in. |
| Rear (Back) track | 1676 mm, 65.98 in. |
| Ride height (ground clearance) | 233 mm, 9.17 in. |
| Minimum turning circle (turning diameter) | 13.8 m, 45.28 ft. |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels permanently, and the front wheels are driven through an electrically or mechanically operated clutch if necessary. |
| Drive wheel | All wheel drive (4×4) |
| Number of gears and type of gearbox | 6 gears, automatic transmission Hydra-Matic |
| Front suspension | Independent torsion bar, double wishbone |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 325×38 mm |
| Rear brakes | Ventilated discs, 325×30 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 265/75 R16; 265/70 R17; 225/75 R17 |
| Wheel rims size | 6.5J x 17; 7J x 16; 7.5J x 17 |
Powertrain & Engine Architecture
The heart of this Sierra 3500HD variant is the 6.0-liter Vortec LY6 V8 engine. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. The LY6 features a cast iron block and aluminum cylinder heads, contributing to its durability. It utilizes a multi-port fuel injection system, delivering fuel directly to each cylinder for efficient combustion. The overhead valve (OHV) valvetrain, while not as technologically advanced as overhead cam designs, is known for its reliability and ease of maintenance. The engine produces 360 horsepower at 5400 rpm and 515 lb-ft of torque at 4200 rpm. The Hydra-Matic 6-speed automatic transmission was the standard transmission offering. This transmission provided smooth shifting and adequate gear ratios for both towing and everyday driving. The 4WD system employed a shift-on-the-fly mechanism, allowing the driver to easily switch between two-wheel drive and four-wheel drive depending on road conditions.
Driving Characteristics
The 6.0L V8 and 6-speed automatic combination in the Sierra 3500HD delivered a capable, if not particularly sporty, driving experience. The engine provided ample torque for hauling heavy loads and navigating challenging terrain. While the horsepower figure was respectable, the truck’s substantial weight (over 5700 lbs) meant acceleration was not its strong suit. The automatic transmission was tuned for practicality rather than performance, with gear changes prioritizing smooth operation and fuel efficiency. Compared to the available Duramax diesel engine, this gasoline V8 offered less torque and lower fuel economy, but it was significantly less expensive to purchase and maintain. The 4WD system provided excellent traction in slippery conditions, making it a suitable choice for those who frequently operate in inclement weather or off-road environments.
Equipment & Trim Levels
The Regular Cab Long Box 6.0L 4WD Sierra 3500HD typically came standard with features geared towards work truck functionality. These included a basic audio system, vinyl upholstery, air conditioning, and power windows and locks. Optional extras included upgraded audio systems, cloth or leather upholstery, power seats, a trailer brake controller, and various towing packages. The interior was functional and durable, designed to withstand the rigors of daily use. The long box provided ample cargo space, making it ideal for hauling building materials, equipment, or other large items.
Chassis & Braking
The Sierra 3500HD featured a heavy-duty chassis designed to handle substantial payloads and towing capacities. The front suspension utilized an independent torsion bar and double wishbone setup, providing a comfortable ride and good handling characteristics. The rear suspension employed a traditional leaf spring design, known for its durability and load-carrying capacity. Braking duties were handled by ventilated disc brakes on all four wheels, providing adequate stopping power even when the truck was heavily loaded. An Anti-lock Braking System (ABS) was standard, enhancing safety and control during emergency braking situations.
Market Reception & Comparison
The 6.0L V8-powered Sierra 3500HD was generally well-received by critics and consumers alike. It was praised for its robust construction, ample towing capacity, and relatively affordable price point. However, it was often criticized for its lower fuel economy compared to the Duramax diesel options. Compared to the 6.6L Duramax diesel, the 6.0L V8 offered significantly less torque, making it less suitable for extremely heavy towing applications. However, the V8 engine was simpler to maintain and repair, and it did not require the expensive diesel exhaust fluid (DEF) system found on later Duramax models.
Legacy
The GMT900 Sierra 3500HD, particularly the 6.0L V8 variants, have proven to be relatively reliable work trucks. The Vortec LY6 engine is known for its durability, and the Hydra-Matic transmission is generally dependable when properly maintained. Today, these trucks can be found in the used car market at relatively affordable prices. They remain a popular choice for those needing a capable and dependable heavy-duty pickup truck for work or personal use. Common maintenance items include regular oil changes, transmission fluid flushes, and inspection of the suspension and braking components. While not as fuel-efficient as modern trucks, the GMT900 Sierra 3500HD continues to offer a compelling combination of capability, durability, and value.
