The Chevrolet Silverado 3500 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 Dual Rear Wheel (DRW) automatic transmission, was a key offering in Chevrolet’s heavy-duty truck lineup from 2007 to 2010. This variant represented a significant capability upgrade over the standard Silverado 1500 and 2500 models, targeting customers requiring substantial towing and hauling capacity. It was positioned as a workhorse for commercial users, farmers, and those with demanding recreational needs, such as large boat or RV towing. The GMT900 generation marked a substantial redesign for Chevrolet’s heavy-duty trucks, focusing on increased strength, improved ride quality, and enhanced diesel engine performance.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 3500 HD |
| Generation | Silverado 3500 HD II (GMT900) Regular Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (365 Hp) 4WD DRW 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 | 8.4 kg/Hp, 119.2 Hp/tonne |
| Weight-to-torque ratio | 3.4 kg/Nm, 292.3 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 | 3062 kg (6750.55 lbs.) |
| Max. weight | 5171 kg (11400.1 lbs.) |
| Max load | 2109 kg (4649.55 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 | 5714 mm (224.96 in.) |
| Width including mirrors | 2436 mm (95.91 in.) |
| Height | 1919 mm (75.55 in.) |
| Wheelbase | 3378 mm (132.99 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 | 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 | 225/75 R17 |
| Wheel rims size | 6.5J x 17 |
INTRODUCTION
The Chevrolet Silverado 3500 HD II (GMT900) with the 6.6L Duramax diesel and automatic transmission represented a significant step forward in heavy-duty truck capability. Introduced in 2007, this iteration of the Silverado 3500 was built on the GMT900 platform, a fully-boxed frame designed for increased rigidity and payload capacity. The “II” designation signifies the mid-cycle refresh within the GMT900 generation. This particular configuration – the regular cab, long box, 4WD DRW, and Duramax/Allison combination – was aimed squarely at professionals and enthusiasts needing maximum towing and hauling performance. It served as a direct competitor to Ford’s Super Duty and Dodge’s Ram HD trucks.
Powertrain & Engine Architecture
The heart of this Silverado 3500 HD II is the Duramax LMM 6.6-liter turbocharged diesel V8 engine. This engine is a significant evolution of the previous LBZ Duramax, featuring a redesigned combustion chamber and improved fuel injection system. The LMM utilizes a common-rail direct injection system, delivering fuel at extremely high pressures for optimized combustion efficiency and reduced emissions. The engine produces 365 horsepower at 3200 rpm and a robust 895 lb-ft of torque at 1600 rpm. The valvetrain employs an overhead valve (OHV) configuration, known for its durability and simplicity. The engine is longitudinally mounted in the chassis.
The Allison 1000 six-speed automatic transmission is specifically designed to handle the immense torque output of the Duramax engine. This transmission is renowned for its durability and smooth shifting characteristics. It features a torque converter lock-up clutch that engages in multiple gears to improve fuel efficiency. The Allison transmission’s gear ratios are optimized for both towing and everyday driving, providing a balance between power and economy. The transmission is electronically controlled, adapting shift points based on vehicle load and driving conditions.
Driving Characteristics
The Silverado 3500 HD II with the Duramax/Allison combination delivers a commanding driving experience. While not designed for sporty handling, the truck provides a stable and controlled ride, even when heavily loaded. The 6.6L Duramax engine provides ample torque from low RPMs, making it ideal for towing and hauling heavy loads. The Allison transmission shifts smoothly and efficiently, contributing to a comfortable driving experience. Compared to the gasoline-powered Silverado 3500 models, the Duramax diesel offers significantly more torque and better fuel economy when towing. Compared to manual transmission equipped Duramax trucks, the automatic provides ease of use, especially in stop-and-go traffic, but may slightly reduce overall fuel efficiency and offer less direct control for some drivers.
Equipment & Trim Levels
The Silverado 3500 HD II Regular Cab Long Box typically came standard with basic work-truck features, including vinyl upholstery, air conditioning, and an AM/FM radio. However, options were plentiful. Popular options included power windows and locks, cruise control, a premium audio system, and upgraded interior trim. The LT trim level added more comfort and convenience features, such as cloth or leather upholstery, heated seats, and a navigation system. The regular cab configuration prioritized functionality and interior space for two occupants, while the long box provided ample cargo capacity.
Chassis & Braking
The GMT900 Silverado 3500 HD II features a fully-boxed frame constructed from high-strength steel, providing a solid foundation for heavy-duty use. The front suspension utilizes an independent torsion bar and double wishbone design, offering a comfortable ride and good handling. The rear suspension employs a traditional leaf spring setup, optimized for load-carrying capacity. The DRW configuration (Dual Rear Wheels) significantly increases stability and load capacity. Braking duties are handled by ventilated disc brakes on all four wheels, with ABS (Anti-lock Braking System) as standard equipment. The front brakes measure 325x38mm, while the rear brakes are 325x30mm.
Market Reception & Comparison
The Silverado 3500 HD II with the Duramax/Allison combination was generally well-received by critics and consumers alike. It was praised for its powerful engine, durable transmission, and impressive towing and hauling capabilities. Fuel economy was considered good for a heavy-duty truck, especially when compared to gasoline-powered alternatives. However, some critics noted the truck’s relatively high price and somewhat stiff ride. Compared to the 6.0L gasoline V8 option, the Duramax diesel offered significantly more torque and better fuel economy when towing, but came at a higher initial cost. Compared to the 8.1L gasoline V8, the Duramax offered comparable horsepower but vastly superior torque and fuel efficiency.
Legacy
The Duramax LMM engine and Allison 1000 transmission have proven to be exceptionally durable and reliable powertrains. Well-maintained examples of the 2007-2010 Silverado 3500 HD II continue to command strong resale values in the used car market. The LMM Duramax is known for its longevity and relatively low maintenance costs, making it a popular choice among truck enthusiasts. While some early LMM engines experienced issues with the fuel injectors, these problems were largely addressed through updated parts and software calibrations. Today, these trucks are still widely used for work and recreation, demonstrating the enduring quality and capability of the GMT900 platform and its powerful Duramax diesel engine.
