The Chevrolet Silverado 2500 HD II (GMT900) Regular Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 365 horsepower and paired with a 4WD automatic transmission, was a key offering in Chevrolet’s heavy-duty truck lineup from 2007 to 2010. This configuration represented a robust work truck option, positioned between the lighter-duty 1500 series and the even more capable 3500 HD models. It was part of the second generation of the GMT900 platform, a significant redesign for Chevrolet’s heavy-duty trucks, focusing on increased capability, improved interior refinement, and enhanced diesel engine technology.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 2500 HD |
| Generation | Silverado 2500 HD II (GMT900) Regular 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 | 2 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.8 kg/Hp, 127.9 Hp/tonne |
| Weight-to-torque ratio | 3.2 kg/Nm, 313.7 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 | 2853 kg (6289.79 lbs.) |
| Max. weight | 4173 kg (9199.89 lbs.) |
| Max load | 1320 kg (2910.1 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 | 5708 mm (224.72 in.) |
| Width including mirrors | 2032 mm (80 in.) |
| Height | 1939 mm (76.34 in.) |
| Wheelbase | 3378 mm (132.99 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) | 13.8 m (45.28 ft.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| 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
The heart of this Silverado 2500 HD was the Duramax LMM 6.6-liter V8 diesel engine. This engine represented a significant evolution of the Duramax platform, incorporating a common-rail fuel injection system capable of extremely high injection pressures for improved combustion efficiency and reduced emissions. The LMM featured a variable geometry turbocharger (VGT) which optimized boost across the engine’s RPM range, contributing to both low-end torque and peak horsepower. The engine utilized an overhead valve (OHV) valvetrain, a design choice favored for its durability and relatively compact size. The Allison 1000 six-speed automatic transmission was specifically designed to handle the high torque output of the Duramax engine. This transmission featured a lock-up torque converter for improved fuel economy 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/Allison combination provided substantial pulling power. While not as quick as gasoline-powered counterparts, the Silverado 2500 HD excelled at towing and hauling heavy loads. The Allison transmission’s six gears helped to keep the engine in its optimal power band, even when loaded. Compared to the 1500 series Silverado, the 2500 HD offered a noticeably firmer ride due to its heavier-duty suspension. The automatic transmission, while convenient, didn’t offer the same level of control as a manual transmission, particularly when descending steep grades with a heavy trailer. The gear ratios were optimized for towing, meaning acceleration from a standstill was not a priority.
Equipment & Trim Levels
The Regular Cab Long Box configuration typically represented the base work truck trim level. Standard features included air conditioning, a basic audio system, and vinyl upholstery. Optional extras included power windows and locks, upgraded audio systems, and various towing packages. The interior was functional and durable, designed to withstand the rigors of commercial use. Higher trim levels, such as the LT and LTZ, offered more luxurious appointments, including leather upholstery, woodgrain trim, and advanced features like navigation systems.
Chassis & Braking
The Silverado 2500 HD featured a robust chassis designed to handle heavy loads. The front suspension utilized an independent torsion bar setup with double wishbones, while the rear suspension employed a traditional leaf spring design. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power even when towing. An Anti-lock Braking System (ABS) was standard equipment. The rear axle ratios varied depending on the specific configuration and intended use, with lower ratios (numerically higher) being favored for towing and higher ratios for general driving.
Market Reception & Comparison
The Duramax diesel engine was widely praised for its reliability and fuel efficiency. Critics generally viewed the Silverado 2500 HD as a capable and durable work truck. Compared to the gasoline-powered Silverado 2500 HD models, the diesel offered significantly better fuel economy, especially when towing. The Duramax/Allison combination was often considered superior to the diesel offerings from Ford and Ram at the time, particularly in terms of long-term reliability. However, the diesel engine carried a significant price premium.
Legacy
The GMT900-era Duramax engines, particularly the LMM variant, have developed a reputation for longevity and durability. Well-maintained examples continue to be highly sought after in the used truck market. The Allison transmission is also known for its robustness. Common maintenance issues include injector failure and turbocharger wear, but these are generally considered manageable with proper preventative maintenance. The Silverado 2500 HD II (GMT900) with the 6.6 Duramax remains a popular choice for those seeking a capable and reliable heavy-duty truck.
