The Chevrolet Silverado 2500 HD II, specifically the Extended Cab Long Box configuration powered by the 6.6-liter Duramax Turbo Diesel V8 engine producing 365 horsepower and paired with a 4WD automatic transmission, was a significant offering in the American heavy-duty truck market from 2007 to 2010. This variant represented a sweet spot for buyers needing substantial towing and hauling capability without opting for the highest, and most expensive, trim levels. It fell within the GMT900 generation of Silverado and Sierra HD trucks, a platform known for its robust construction and work-oriented design. This particular configuration aimed to balance power, efficiency, and practicality for a broad range of users, from contractors to those requiring a powerful personal vehicle.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 2500 HD |
| Generation | Silverado 2500 HD II (GMT900) Extended Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (365 Hp) 4WD Automatic |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8.3 kg/Hp, 120.2 Hp/tonne |
| Weight-to-torque ratio | 3.4 kg/Nm, 294.8 Nm/tonne |
| Power | 365 Hp @ 3200 rpm |
| Power per litre | 55.3 Hp/l |
| Torque | 895 Nm @ 1600 rpm (660.12 lb.-ft. @ 1600 rpm) |
| Maximum engine speed | 3450 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax LMM |
| Engine displacement | 6599 cm3 (402.7 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103 mm (4.06 in.) |
| Piston Stroke | 99 mm (3.9 in.) |
| Compression ratio | 16.8:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | OHV |
| Engine oil capacity | 9.5 l (10.04 US qt | 8.36 UK qt) |
| Coolant | 24 l (25.36 US qt | 21.12 UK qt) |
| Kerb Weight | 3036 kg (6693.23 lbs.) |
| Max. weight | 4173 kg (9199.89 lbs.) |
| Max load | 1137 kg (2506.66 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%) | 5897 kg (13000.66 lbs.) |
| Length | 6330 mm (249.21 in.) |
| Width including mirrors | 2032 mm (80 in.) |
| Height | 1946 mm (76.61 in.) |
| Wheelbase | 4001 mm (157.52 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 m (52.49 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 Allison |
| 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 this Silverado 2500 HD II lay the Duramax LMM 6.6-liter V8 diesel engine. This engine was a significant evolution of the previous LBZ Duramax, incorporating a more robust block, redesigned cylinder heads, and a more efficient turbocharger. The LMM utilized a common-rail fuel injection system, delivering fuel at extremely high pressures for optimized combustion and reduced emissions. The engine featured an overhead valve (OHV) valvetrain, a design choice favored for its durability and simplicity. The turbocharger and intercooler worked in tandem to increase air density, boosting power and torque output. The Allison 1000 six-speed automatic transmission was specifically designed to handle the immense torque produced by the Duramax engine. This transmission featured a lock-up torque converter for improved fuel efficiency at highway speeds and heavy-duty internal components for reliability under demanding conditions.
Driving Characteristics
The 365 horsepower and 895 lb-ft of torque delivered by the Duramax engine and Allison transmission combination provided substantial performance. While not as quick as gasoline-powered trucks, the Silverado 2500 HD II excelled in towing and hauling. The automatic transmission offered smooth and predictable shifts, making it easy to manage heavy loads. Compared to the manual transmission options, the automatic provided greater convenience, especially in stop-and-go traffic. However, some drivers preferred the more direct feel and control offered by a manual gearbox. The gear ratios were optimized for towing, providing ample low-end torque for pulling heavy trailers. The 4WD system ensured excellent traction in various conditions, making it a capable work truck year-round.
Equipment & Trim Levels
The Silverado 2500 HD II in this configuration typically came standard with features like air conditioning, power windows and locks, and a basic audio system. The Extended Cab provided additional interior space compared to the regular cab models, offering more comfortable seating for passengers. Upholstery was typically vinyl or cloth, with optional leather upgrades available. Common optional extras included a navigation system, upgraded audio systems, heated seats, and various towing packages. The trim level often dictated the level of interior refinement and exterior styling, with higher trims featuring chrome accents and more luxurious materials.
Chassis & Braking
The Silverado 2500 HD II featured a robust chassis designed to withstand heavy loads. The front suspension utilized an independent torsion bar setup with double wishbones, 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 rear brakes were slightly smaller in diameter than the front brakes, reflecting the weight distribution of the truck.
Market Reception & Comparison
The Silverado 2500 HD II with the Duramax engine and Allison transmission was generally well-received by critics and consumers alike. It was praised for its powerful engine, smooth transmission, and robust construction. Fuel economy, while not a primary concern for heavy-duty truck buyers, was considered reasonable for its class. Compared to the gasoline-powered Silverado 2500 HD models, the Duramax diesel offered significantly more torque and better fuel efficiency when towing. The LMM Duramax was also considered more reliable than some of its predecessors, addressing concerns about previous engine designs. Compared to competitors like the Ford Super Duty and Ram Heavy Duty trucks, the Silverado 2500 HD II offered a competitive combination of power, features, and value.
Legacy
The Duramax LMM engine and Allison transmission pairing proved to be exceptionally durable, and well-maintained examples of the 2007-2010 Silverado 2500 HD II continue to be sought after in the used truck market today. These trucks are known for their longevity and ability to handle demanding tasks. While some maintenance items, such as the fuel injectors and turbocharger, may require attention after many years of service, the overall reliability of the powertrain is highly regarded. The GMT900 platform established a strong reputation for Chevrolet in the heavy-duty truck segment, paving the way for future generations of Silverado HD models.
