The Chevrolet Silverado 2500 HD II, specifically the Extended Cab Standard Box configuration powered by the 6.6-liter Duramax turbodiesel 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 larger, more expensive crew cab models. 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 at customers who required a powerful, capable truck for both commercial and personal use, prioritizing functionality and durability.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 2500 HD |
| Generation | Silverado 2500 HD II (GMT900) Extended Cab Standard 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 | 8.2 kg/Hp, 122.6 Hp/tonne |
| Weight-to-torque ratio | 3.3 kg/Nm, 300.5 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 | 2978 kg (6565.37 lbs.) |
| Max. weight | 4173 kg (9199.89 lbs.) |
| Max load | 1195 kg (2634.52 lbs.) |
| Trunk (boot) space – maximum | 1718 l (60.67 cu. ft.) |
| Fuel tank capacity | 98 l (25.89 US gal | 21.56 UK gal) |
| Permitted trailer load with brakes (12%) | 5897 kg (13000.66 lbs.) |
| Length | 5850 mm (230.31 in.) |
| Width including mirrors | 2032 mm (80 in.) |
| Height | 1951 mm (76.81 in.) |
| Wheelbase | 3645 mm (143.5 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) | 14.5 m (47.57 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
The heart of this Silverado 2500 HD variant is the Duramax LMM 6.6-liter V8 turbodiesel engine. This engine represented a significant evolution of the Duramax design, incorporating a common-rail fuel injection system for improved efficiency and reduced emissions. The LMM featured a variable geometry turbocharger (VGT) which optimized boost across the engine’s RPM range, contributing to both increased power and improved low-end torque. The engine utilized a robust cast iron block and cylinder heads, designed for longevity and high-stress applications. The overhead valve (OHV) valvetrain, while traditional, was known for its simplicity and reliability. 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 durability.
Driving Characteristics
The 365 horsepower and 895 lb-ft of torque delivered by the Duramax engine and Allison transmission combination provided substantial performance for a heavy-duty truck. While not as quick as gasoline-powered alternatives, the Silverado 2500 HD excelled in towing and hauling. The automatic transmission, while smooth, was tuned for work rather than sport, prioritizing consistent power delivery over rapid shifts. Compared to the 1.8L gasoline engine options available in the lighter-duty Silverado 1500, this Duramax variant offered a completely different driving experience, focused on effortless pulling power. Compared to higher-output Duramax variants (later models exceeding 400 hp), this version offered a balance between capability and cost, making it accessible to a wider range of buyers. The 4WD system provided excellent traction in various conditions, making it suitable for both on-road and off-road use.
Equipment & Trim Levels
The Extended Cab Standard Box configuration typically came with a relatively utilitarian interior, focused on durability and functionality. Standard features included air conditioning, a basic audio system, and vinyl upholstery. Higher trim levels, such as the LT, added features like cloth or leather upholstery, power windows and locks, and upgraded audio systems. Optional extras included a navigation system, a sunroof, and various towing packages. The extended cab provided additional storage space behind the front seats, useful for tools or personal belongings. The standard box offered a good balance between cargo capacity and overall vehicle length.
Chassis & Braking
The Silverado 2500 HD II utilized a fully boxed frame for exceptional strength and rigidity. The front suspension featured an independent torsion bar setup with double wishbone components, providing a comfortable ride while maintaining robust load-carrying capacity. The rear suspension employed a traditional leaf spring design, optimized for heavy-duty applications. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power even when heavily loaded. An Anti-lock Braking System (ABS) was standard equipment. The rear axle ratios were typically chosen to optimize either fuel economy or towing capacity, depending on the specific configuration.
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 robust construction, powerful engine, and capable towing performance. Fuel economy, while not a primary concern for heavy-duty truck buyers, was considered acceptable for a vehicle of its size and capability. Compared to the gasoline-powered Silverado 2500 HD models, the Duramax variant offered significantly more torque and better fuel economy when towing heavy loads. Reliability was generally good, although the Duramax engine’s emissions control systems (particularly the particulate filter) could be prone to issues over time.
Legacy
The Duramax LMM engine and Allison transmission combination proved to be exceptionally durable and reliable. Many of these trucks remain in service today, often with high mileage. The GMT900 platform Silverado 2500 HD II is still a popular choice for those seeking a capable and affordable heavy-duty truck. The LMM Duramax engine is considered by many to be one of the most reliable Duramax engines ever produced, and parts availability remains good. On the used car market, these trucks command a premium compared to gasoline-powered alternatives, reflecting their reputation for longevity and capability.
