2007-2010 Chevrolet Silverado 3500 HD II (GMT900) Extended Cab Long Box 6.6 Duramax TD V8 (365 Hp) 4WD SRW Automatic

Technical Specifications

The 2007-2010 Chevrolet Silverado 3500 HD II, specifically the Extended Cab Long Box configuration with the 6.6L Duramax diesel and Allison automatic transmission, was designed to be a workhorse. It built upon the foundation of the GMT900 platform, which brought a more robust frame, updated styling, and a significantly improved interior compared to its predecessor. This particular variant aimed to provide a balance between heavy-duty capability and a degree of comfort and practicality for daily use. The Extended Cab offered additional passenger space, while the Long Box provided ample cargo capacity. This model was primarily sold in North America, where demand for heavy-duty trucks remained strong, particularly among those involved in construction, agriculture, and recreational towing.

Powertrain & Engine Architecture

At the heart of this Silverado 3500 HD II lies 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 boasts 365 horsepower at 3200 rpm and a substantial 895 lb-ft of torque at 1600 rpm. The valvetrain employs an overhead valve (OHV) configuration, known for its simplicity and durability.

The engine is mated to the Allison 1000 Series 6-speed automatic transmission, renowned for its robustness and ability to handle high torque loads. This transmission features electronically controlled shifting and a lock-up torque converter for improved fuel efficiency. The Allison transmission’s gear ratios are optimized for both towing and highway cruising, providing a balance between power delivery and fuel economy. The 4WD system utilizes an electronically controlled transfer case, allowing the driver to switch between two-wheel drive, four-wheel drive high, and four-wheel drive low ranges.

Driving Characteristics

The Silverado 3500 HD II with the Duramax/Allison combination delivers a driving experience that prioritizes capability and stability. While not a performance-oriented truck, the abundant torque provides effortless acceleration, even when heavily loaded. The Allison transmission shifts smoothly and decisively, contributing to a comfortable driving experience. Compared to the gasoline-powered Silverado 3500 HD models, the Duramax diesel offers significantly more low-end torque, making it ideal for towing and hauling. However, the diesel engine is noticeably louder and produces more vibration than its gasoline counterpart. The 6-speed automatic, while capable, isn’t as quick-shifting as some newer transmissions, but its durability is a key strength. The truck’s substantial weight and long wheelbase contribute to a stable and planted feel, even on rough roads.

Equipment & Trim Levels

The Silverado 3500 HD II offered a range of trim levels, with the 6.6L Duramax/Allison combination typically found in the LT and LTZ trims. Standard features included air conditioning, power windows and locks, a CD player, and cloth upholstery. The LTZ trim added features such as leather upholstery, heated front seats, a premium sound system, and chrome exterior accents. Optional extras included a navigation system, a sunroof, and a rear-seat entertainment system. The Extended Cab configuration provided a small rear seat suitable for occasional passengers, while the Long Box offered a generous cargo bed length for hauling large items.

Chassis & Braking

The Silverado 3500 HD II features a fully boxed frame constructed from high-strength steel, providing a solid foundation for the truck’s heavy-duty capabilities. The front suspension utilizes an independent torsion bar setup with double wishbone control arms, while the rear suspension employs a traditional leaf spring design. This combination provides a comfortable ride, even when the truck is loaded. 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 325×38 mm, while the rear brakes are 325×30 mm. The truck’s substantial weight necessitates a robust braking system to ensure safe and controlled stopping power.

Market Reception & Comparison

The 2007-2010 Chevrolet 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, robust transmission, and impressive towing and hauling capabilities. Compared to the gasoline-powered Silverado 3500 HD models, the Duramax diesel offered superior fuel economy when towing heavy loads. However, the diesel engine’s higher initial cost and potential maintenance expenses were drawbacks for some buyers. Compared to competitors like the Ford Super Duty and Ram Heavy Duty, the Silverado 3500 HD II offered a competitive combination of features, performance, and value.

Legacy

The Duramax LMM engine and Allison 1000 Series 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 ability to withstand high mileage. However, potential buyers should be aware of potential issues such as injector failure and turbocharger wear. Overall, this Silverado 3500 HD II variant remains a popular choice for those seeking a capable and reliable heavy-duty truck.