The Chevrolet Silverado 3500 HD II, specifically the Extended Cab Long Box configuration powered by the 6.6-liter Duramax Turbo Diesel V8 engine paired with an Allison automatic transmission, represents a significant iteration in Chevrolet’s heavy-duty truck lineage. Produced from 2007 through 2010 (GMT900 platform), this variant was aimed squarely at the demanding needs of commercial users, farmers, and individuals requiring substantial towing and hauling capabilities. It occupied a premium position within the Silverado 3500 HD lineup, offering a substantial step up in performance and capacity compared to gasoline-powered options and lighter-duty trims.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 3500 HD |
| Generation | Silverado 3500 HD II (GMT900) Extended Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (365 Hp) DRW 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 | 8.6 kg/Hp, 116.3 Hp/tonne |
| Weight-to-torque ratio | 3.5 kg/Nm, 285.1 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 | 3139 kg (6920.31 lbs.) |
| Max. weight | 5171 kg (11400.1 lbs.) |
| Max load | 2032 kg (4479.79 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%) | 5897 kg (13000.66 lbs.) |
| Length | 6330 mm (249.21 in.) |
| Width including mirrors | 2436 mm (95.91 in.) |
| Height | 1931 mm (76.02 in.) |
| Wheelbase | 4001 mm (157.52 in.) |
| Front track | 1742 mm (68.58 in.) |
| Rear (Back) track | 1897 mm (74.69 in.) |
| Ride height (ground clearance) | 233 mm (9.17 in.) |
| Drivetrain Architecture | Rear wheel drive. Internal Combustion engine. |
| 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 | 225/75 R17 |
| Wheel rims size | 6.5J x 17 |
INTRODUCTION
The 2007-2010 Chevrolet Silverado 3500 HD II, in its Extended Cab Long Box configuration with the 6.6L Duramax diesel and Allison automatic, was a workhorse designed for serious tasks. Built on the GMT900 platform, this generation represented a significant upgrade in terms of capability and refinement over its predecessors. The “II” designation signifies a mid-cycle refresh, incorporating improvements to the interior, exterior styling, and powertrain. This particular combination – the extended cab, long bed, Duramax diesel, and Allison transmission – was a popular choice for those needing a versatile and powerful truck for both commercial and personal use. It was positioned as a premium offering, bridging the gap between the standard work trucks and the more luxurious trims.
Powertrain & Engine Architecture
At the heart of this Silverado 3500 HD lies the Duramax LMM 6.6-liter turbocharged diesel V8. This engine, a product of a joint venture between General Motors and Isuzu, is renowned for its durability and torque output. The LMM featured a redesigned combustion chamber and improved fuel injection system compared to earlier Duramax engines. It utilized a common-rail direct injection system, delivering fuel at extremely high pressures for optimized combustion. The engine also incorporated a variable geometry turbocharger (VGT) and an intercooler to maximize power and efficiency. The OHV valvetrain, while traditional, proved to be robust and reliable. The Allison 1000 series 6-speed automatic transmission was specifically engineered to handle the immense torque produced by the Duramax engine. This transmission featured a lock-up torque converter for improved fuel economy and a heavy-duty cooling system to prevent overheating under demanding conditions.
Driving Characteristics
The Silverado 3500 HD with the 6.6L Duramax and Allison automatic delivered a driving experience focused on capability rather than outright speed. While 365 horsepower is respectable, the true strength of this powertrain lies in its 895 lb-ft of torque. This abundant torque allowed for effortless towing and hauling, even with heavy loads. The Allison transmission provided smooth and precise shifts, and the gear ratios were optimized for both pulling power and highway cruising. Compared to the gasoline-powered Silverado 3500 HD models, the diesel offered significantly more low-end grunt and superior fuel economy when towing. Compared to manual transmission equipped Duramax trucks, the automatic offered ease of use, particularly in stop-and-go traffic, but some drivers noted a slight reduction in fuel economy and a less direct connection to the engine.
Equipment & Trim Levels
The Extended Cab configuration added rear seats and increased interior storage space compared to the regular cab models. Standard features typically included air conditioning, power windows and locks, an AM/FM stereo, and a tilt steering wheel. The interior upholstery was typically cloth, but leather options were available. Higher trim levels, such as the LT and LTZ, added features like heated seats, a premium sound system, navigation, and chrome exterior accents. Optional extras included a sunroof, a backup camera, and various towing packages. The Long Box provided ample cargo space for hauling materials or equipment.
Chassis & Braking
The Silverado 3500 HD 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, optimized for 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. Due to the truck’s weight and intended use, rear drum brakes were common on lower trims, while higher trims often featured rear disc brakes. The Dual Rear Wheel (DRW) configuration, as found in this variant, further enhanced stability and load-carrying capacity.
Market Reception & Comparison
The 2007-2010 Silverado 3500 HD with the Duramax diesel and Allison automatic was generally well-received by critics and consumers alike. It was praised for its powerful engine, smooth transmission, and impressive towing capacity. Fuel economy, while not exceptional, was considered good for a heavy-duty truck. Compared to the Ford Super Duty and Ram 3500, the Silverado 3500 HD offered a competitive combination of performance, features, and price. Some critics noted that the interior design was somewhat dated compared to its rivals, but the overall build quality and reliability were generally praised.
Legacy
The Duramax LMM engine and Allison transmission pairing have proven to be exceptionally durable and reliable. Properly maintained examples of this powertrain can easily exceed 200,000 miles. On the used car market, these Silverado 3500 HDs remain highly sought after, particularly those with well-documented maintenance histories. They continue to be valued for their ability to handle demanding tasks and their relatively low cost of ownership compared to newer heavy-duty trucks. The GMT900 platform, while superseded by newer generations, established a strong foundation for Chevrolet’s heavy-duty truck lineup and cemented the Duramax diesel’s reputation as a workhorse engine.
