2007-2010 GMC Sierra 2500HD III (GMT900) Regular Cab Long Box 6.0 V8 (360 Hp) Automatic

The GMC Sierra 2500HD III (GMT900) Regular Cab Long Box, equipped with the 6.0-liter V8 engine and automatic transmission, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2007 to 2010, this variant occupied a crucial position in the American full-size pickup market, catering to buyers needing substantial towing and hauling capabilities without the added complexity or cost of four-wheel drive or crew cab configurations. It was part of the GMT900 platform generation, a substantial redesign for GMC’s heavy-duty trucks, focusing on increased strength, improved refinement, and enhanced capability.

Technical Specifications

INTRODUCTION

The GMC Sierra 2500HD III, specifically the Regular Cab Long Box configuration with the 6.0-liter V8 and automatic transmission, was a work-focused truck designed for the American market. Introduced as part of the GMT900 series from 2007-2010, it represented a significant upgrade over its predecessor in terms of capability and refinement. This model served as a mainstay for owners requiring a robust, reliable pickup for towing, hauling, and general work duties. It slotted into the lineup as a mid-range offering, providing a balance between affordability and capability, positioned below the more expensive four-wheel-drive and diesel-powered models, but above the base work truck trims.

Powertrain & Engine Architecture

At the heart of this Sierra 2500HD lies the Vortec LY6 6.0-liter V8 engine. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. The LY6 utilizes a cast iron block and aluminum cylinder heads, contributing to its durability. It features a 9.6:1 compression ratio and utilizes multi-port fuel injection for precise fuel delivery. The overhead valve (OHV) valvetrain, while not as technologically advanced as overhead cam designs, is known for its reliability and ease of maintenance. The engine produces 360 horsepower at 5400 rpm and 515 Nm (379.84 lb-ft) of torque at 4200 rpm. The engine is paired with a 6-speed Hydra-Matic automatic transmission, a robust unit designed to handle the high torque output of the V8. This transmission features electronically controlled shifting for smoother operation and improved fuel efficiency compared to older designs.

Driving Characteristics

The 6.0-liter V8 and 6-speed automatic combination in the Sierra 2500HD delivered a capable, if not particularly sporty, driving experience. The truck’s substantial weight (2379 kg / 5244.8 lbs) meant acceleration was brisk rather than quick. The automatic transmission was tuned for work, prioritizing smooth shifts and reliable operation over aggressive downshifts. The gear ratios were optimized for towing and hauling, providing ample low-end torque for getting heavy loads moving. Compared to the available Duramax diesel engine, the 6.0L V8 offered less torque and lower fuel economy, but it was significantly less expensive to purchase and maintain. Compared to the manual transmission equipped versions, the automatic offered greater convenience, especially in stop-and-go traffic, but at the expense of some driver control and potentially slightly reduced fuel economy.

Equipment & Trim Levels

The Regular Cab Long Box 6.0L Automatic Sierra 2500HD typically came standard with features like air conditioning, a basic audio system, and vinyl upholstery. The interior was functional and durable, designed to withstand the rigors of work use. Optional extras included power windows and locks, upgraded audio systems, cruise control, and a towing package. Higher trim levels, such as the SLT, added features like leather upholstery, woodgrain interior trim, and premium audio systems. The standard bench seat configuration provided seating for two passengers. The long box bed offered ample cargo space, measuring 2138 liters (75.5 cu. ft.).

Chassis & Braking

The Sierra 2500HD featured a fully boxed frame for increased rigidity and strength. The front suspension utilized an independent torsion bar and double wishbone setup, providing a relatively comfortable ride for a heavy-duty truck. The rear suspension employed a traditional leaf spring design, optimized for load-carrying capacity. Braking duties were handled by ventilated discs at all four corners, with ABS (Anti-lock Braking System) as standard equipment. The front brakes measured 325×38 mm, while the rear brakes were slightly smaller at 325×30 mm. The steering system was a cone worm with recirculation balls, providing a solid and predictable feel.

Market Reception & Comparison

The GMC Sierra 2500HD with the 6.0-liter V8 and automatic transmission was generally well-received by critics and consumers. It was praised for its robust construction, ample power, and comfortable ride. However, its fuel economy was a common criticism, as expected for a large, heavy-duty truck. Compared to the diesel-powered Duramax models, the 6.0L V8 offered a lower purchase price and simpler maintenance, making it an attractive option for buyers who didn’t require the ultimate in towing capacity or fuel efficiency. The 6.0L engine was considered more reliable than some earlier iterations of GM’s V8 engines, but still required regular maintenance to prevent oil consumption issues.

Legacy

The GMT900-generation Sierra 2500HD, including the 6.0-liter V8 automatic variant, has proven to be a durable and reliable truck. On the used car market, these trucks remain popular due to their affordability and capability. The 6.0L Vortec engine, while not the most fuel-efficient, is known for its longevity and relatively straightforward maintenance. Common issues include oil consumption and occasional sensor failures, but these are generally manageable with proper maintenance. The Hydra-Matic transmission is also considered reliable, provided it has been regularly serviced. Today, these trucks continue to be used for work and personal use, demonstrating their enduring appeal and robust design.