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

Technical Specifications

The Chevrolet Silverado 3500 HD II (GMT900) Extended 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, represents a significant iteration in Chevrolet’s heavy-duty truck lineage. Produced from 2007 to 2010, this variant occupied a crucial position in the Silverado 3500 HD lineup, catering to buyers requiring substantial towing and hauling capabilities. It was part of the GMT900 generation, a platform known for its robust construction and enhanced payload capacity compared to its predecessors. This particular configuration was aimed at professionals and individuals needing a powerful, reliable work truck without necessarily opting for the highest trim levels.

Powertrain & Engine Architecture

The heart of this Silverado 3500 HD II is the Duramax LMM 6.6-liter V8 turbodiesel engine. This engine represented a significant refinement of the previous LBZ Duramax, incorporating a more robust crankshaft, redesigned pistons, and an improved cooling system. The LMM utilized a common-rail fuel injection system, delivering fuel at extremely high pressures for optimized combustion and reduced emissions. The engine’s valvetrain employed an overhead valve (OHV) configuration, known for its simplicity and durability. A variable geometry turbocharger and intercooler further enhanced performance and efficiency. The Allison 1000 six-speed automatic transmission was specifically designed to handle the engine’s substantial torque output. This transmission featured a lock-up torque converter for improved fuel economy at highway speeds and provided smooth, reliable shifting even under heavy loads.

Driving Characteristics

The 365 horsepower and 895 lb-ft of torque delivered by the Duramax LMM engine, coupled with the Allison automatic transmission, provided a compelling driving experience. While not as quick as lighter-duty trucks or those equipped with gasoline engines, the Silverado 3500 HD II excelled in towing and hauling. The automatic transmission’s gear ratios were optimized for maximizing torque at lower RPMs, making it easy to pull heavy trailers or transport large payloads. Compared to manual transmission versions, the automatic offered greater convenience, particularly in stop-and-go traffic. However, some drivers preferred the more direct control offered by a manual gearbox. The Dual Rear Wheel (DRW) configuration provided enhanced stability when towing or carrying heavy loads, distributing the weight more evenly across the rear axle.

Equipment & Trim Levels

The Silverado 3500 HD II Extended Cab Long Box with the Duramax engine typically came standard with features like air conditioning, power windows and locks, and a basic audio system. The Extended Cab configuration provided additional rear seating and storage space compared to the regular cab models. Interior upholstery was typically vinyl or cloth, with optional leather upgrades available. Popular options included a navigation system, upgraded audio systems, heated seats, and various towing packages. The trim level – often a Work Truck (WT) or LT – dictated the level of standard equipment and available options. The WT trim was more basic and focused on functionality, while the LT trim offered more comfort and convenience features.

Chassis & Braking

The GMT900 platform featured a fully boxed frame constructed from high-strength steel, providing a solid foundation for heavy-duty applications. The front suspension utilized an independent torsion bar setup with double wishbones, offering 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, with ABS (Anti-lock Braking System) as standard equipment. The DRW configuration provided a wider track and increased braking capacity compared to single rear wheel (SRW) models.

Market Reception & Comparison

The Silverado 3500 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 impressive towing and hauling capabilities. Fuel economy, while not exceptional, was considered reasonable for a heavy-duty truck of its size and capability. Compared to the gasoline-powered Silverado 3500 HD models, the Duramax diesel offered significantly more torque and better fuel economy when towing. Compared to competitors like the Ford Super Duty and Ram Heavy Duty trucks, the Silverado 3500 HD II was often seen as a strong contender, offering a compelling combination of performance, reliability, and value.

Legacy

The Duramax LMM engine and Allison transmission pairing proved to be exceptionally durable and reliable. Many of these trucks remain in service today, having accumulated hundreds of thousands of miles. While some maintenance items, such as the fuel injectors and turbocharger, may require attention over time, the core powertrain is known for its longevity. On the used car market, these Silverado 3500 HD II models continue to command respectable prices, reflecting their reputation for reliability and capability. They remain a popular choice for those seeking a powerful and dependable work truck.