The GMC Sierra 2500HD III (GMT900) Crew Cab Long Box, equipped with the 6.0-liter V8 engine and automatic transmission, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2007 to 2010, this variant occupied a sweet spot in the lineup, offering a balance of capability, comfort, and affordability for buyers needing serious towing and hauling capacity. It was part of the GMT900 platform generation, a substantial redesign that focused on improving interior space, ride quality, and overall refinement compared to its predecessors. This particular configuration was aimed at both commercial users and private owners who required a robust truck for work and recreational purposes.
Technical Specifications
| Brand | GMC |
| Model | Sierra 2500HD |
| Generation | Sierra 2500HD III (GMT900) Crew Cab Long Box |
| Type (Engine) | 6.0 V8 (360 Hp) Automatic |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 8.3 kg/Hp, 120.8 Hp/tonne |
| Weight-to-torque ratio | 5.8 kg/Nm, 172.8 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 | 2980 kg, 6569.78 lbs. |
| Max. weight | 4173 kg, 9199.89 lbs. |
| Max load | 1193 kg, 2630.11 lbs. |
| Trunk (boot) space – maximum | 2138 l, 75.5 cu. ft. |
| Fuel tank capacity | 129 l, 34.08 US gal | 28.38 UK gal |
| Permitted trailer load with brakes (12%) | 5625 kg, 12401 lbs. |
| Length | 6572 mm, 258.74 in. |
| Width including mirrors | 2436 mm, 95.91 in. |
| Height | 1930 mm, 75.98 in. |
| Wheelbase | 4242 mm, 167.01 in. |
| Front track | 1744 mm, 68.66 in. |
| Rear (Back) track | 1676 mm, 65.98 in. |
| Ride height (ground clearance) | 243 mm, 9.57 in. |
| Minimum turning circle (turning diameter) | 16.8 m, 55.12 ft. |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| 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 | 245/75 R16; 265/75 R17 |
| Wheel rims size | 6.5J x 16; 7.5J x 17 |
Powertrain & Engine Architecture
At the heart of the Sierra 2500HD was the Vortec LY6 6.0-liter V8 engine. This engine, a member of GM’s Vortec family, was known for its robust construction and relatively simple design. It featured a cast iron block and aluminum cylinder heads, contributing to its durability. The LY6 utilized 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, was reliable and provided ample low-end torque. The engine produced 360 horsepower at 5400 rpm and 515 Nm (379.84 lb-ft) of torque at 4200 rpm. This power was channeled through a six-speed Hydra-Matic automatic transmission, specifically tuned for heavy-duty applications. The transmission’s gear ratios were optimized for towing and hauling, providing strong acceleration from a standstill and maintaining comfortable cruising speeds on the highway.
Driving Characteristics
The 6.0-liter V8 and automatic transmission combination delivered a driving experience focused on capability rather than outright speed. While not as quick as lighter-duty trucks or those equipped with the optional Duramax diesel engine, the Sierra 2500HD provided ample power for most tasks. The automatic transmission shifted smoothly, and the torque converter multiplied engine torque, making it easy to get heavy loads moving. Compared to manual transmission versions, the automatic offered greater convenience, especially in stop-and-go traffic or when towing on hilly terrain. However, the automatic did result in a slight reduction in fuel economy compared to the manual. The truck’s substantial weight and long wheelbase contributed to a comfortable ride, but also made handling less nimble than smaller pickups.
Equipment & Trim Levels
The Sierra 2500HD Crew Cab Long Box with the 6.0-liter V8 typically came standard with features like air conditioning, power windows and locks, a CD player, and cloth upholstery. The Crew Cab configuration offered spacious seating for five passengers, making it a practical choice for families or work crews. Optional extras included leather upholstery, a premium sound system, a navigation system, and a power sunroof. Trim levels varied, with the base model offering essential features, while higher trims added more luxury and convenience items. The long box provided ample cargo space for hauling materials or equipment.
Chassis & Braking
The Sierra 2500HD featured a robust chassis designed to withstand heavy loads. The front suspension utilized an independent torsion bar and double wishbone setup, providing a comfortable ride and good handling. 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 ample stopping power. An anti-lock braking system (ABS) was standard, enhancing safety during emergency braking situations. The truck’s wide track and long wheelbase contributed to its stability, especially when towing.
Market Reception & Comparison
The GMC Sierra 2500HD with the 6.0-liter V8 and automatic transmission was generally well-received by critics and consumers. It was praised for its strong towing capacity, comfortable ride, and spacious interior. However, some reviewers noted that the fuel economy was relatively poor compared to diesel-powered trucks. Compared to the Duramax diesel option, the 6.0-liter V8 offered a lower initial cost but significantly less torque and fuel efficiency. The 6.0L was often seen as a good choice for those who didn’t require the ultimate in towing power but still needed a capable heavy-duty truck.
Legacy
The Vortec LY6 6.0-liter V8 proved to be a relatively reliable engine, although some owners have reported issues with oil consumption and active fuel management (AFM) systems. The Hydra-Matic automatic transmission is also generally considered durable, but regular maintenance, including fluid changes, is crucial for long-term reliability. Today, these trucks can be found on the used car market at relatively affordable prices, making them a popular choice for those seeking a capable and affordable heavy-duty pickup. While not as fuel-efficient as modern trucks, the Sierra 2500HD remains a workhorse capable of handling a wide range of tasks.
