The Chevrolet Silverado 3500 HD III (K2XX) Double Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 397 horsepower and paired with an Allison automatic transmission, represents a significant iteration in Chevrolet’s heavy-duty truck lineage. Produced from 2015 to 2017, this variant occupied a premium position within the Silverado 3500 HD lineup, targeting buyers requiring substantial towing and hauling capabilities without sacrificing everyday usability. It was part of the third generation of the K2XX platform, known for its enhanced strength, refinement, and technology compared to its predecessors.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 3500 HD |
| Generation | Silverado 3500 HD III (K2XX) Double Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) SRW Automatic |
| Start of production | 2015 |
| End of production | 2017 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8.2 kg/Hp, 121.7 Hp/tonne |
| Weight-to-torque ratio | 3.1 kg/Nm, 318 Nm/tonne |
| Power | 397 Hp @ 3000 rpm |
| Power per litre | 60.2 Hp/l |
| Torque | 1037 Nm @ 1600 rpm, 764.85 lb.-ft. @ 1600 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax LML |
| 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 | 16:1 |
| 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 | 22.4 l, 23.67 US qt | 19.71 UK qt |
| Kerb Weight | 3261 kg, 7189.27 lbs |
| Max. weight | 5080 kg, 11199.48 lbs |
| Max load | 1819 kg, 4010.21 lbs |
| Trunk (boot) space – maximum | 2162 l, 76.35 cu. ft. |
| Fuel tank capacity | 136 l, 35.93 US gal | 29.92 UK gal |
| Permitted trailer load with brakes (12%) | 6577 kg, 14499.8 lbs |
| Length | 6321 mm, 248.86 in. |
| Width including mirrors | 2045 mm, 80.51 in. |
| Height | 1981 mm, 77.99 in. |
| Wheelbase | 4017 mm, 158.15 in. |
| Front track | 1748 mm, 68.82 in. |
| Rear (Back) track | 1709 mm, 67.28 in. |
| Ride height (ground clearance) | 221 mm, 8.7 in. |
| Minimum turning circle (turning diameter) | 16.2 m, 53.15 ft. |
| 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, 355×40 mm |
| Rear brakes | Ventilated discs, 373×34 mm |
| Tires size | 235/80 R17; 265/70 R18 |
| Wheel rims size | 7.5J x 17; 8J x 18 |
INTRODUCTION
The 2015-2017 Chevrolet Silverado 3500 HD Double Cab Long Box with the 6.6L Duramax diesel and Allison automatic transmission was a workhorse designed for demanding tasks. Positioned as a premium offering within the Silverado 3500 HD range, it catered to customers needing substantial towing capacity and payload, such as those involved in construction, agriculture, or recreational activities like hauling large trailers. This generation (K2XX) represented a significant upgrade over the previous Silverado HD models, focusing on increased strength, improved ride quality, and enhanced interior features. The Double Cab configuration offered a balance between passenger space and bed length, making it a versatile option for both work and family use.
Powertrain & Engine Architecture
At the heart of this Silverado 3500 HD variant lies the Duramax LML 6.6-liter turbocharged diesel V8 engine. This engine is renowned for its robust construction and impressive torque output. The LML featured a revised turbocharger, improved fuel injection system, and enhanced glow plug system compared to earlier Duramax engines. The engine utilizes a diesel commonrail fuel injection system, delivering highly pressurized fuel directly into the cylinders for efficient combustion. The overhead valve (OHV) valvetrain, while traditional, proved durable and reliable. The Allison 1000 six-speed automatic transmission is a key component, specifically engineered to handle the high torque output of the Duramax engine. This transmission is known for its durability and smooth shifting characteristics, and features a lock-up torque converter for improved fuel efficiency at highway speeds. The transmission’s gear ratios are optimized for both towing and everyday driving, providing ample power across a wide range of speeds.
Driving Characteristics
The combination of the 397 horsepower and 764.85 lb-ft of torque delivered by the Duramax engine and Allison transmission resulted in a truck capable of impressive performance, even when heavily loaded. While not as quick as gasoline-powered counterparts, the Silverado 3500 HD offered substantial pulling power and a relaxed driving experience. The Allison transmission’s smooth shifts minimized jerkiness, and the engine’s abundant low-end torque made towing feel effortless. Compared to the 6.0L gasoline V8 option, the Duramax provided significantly more torque, making it the preferred choice for heavy-duty applications. Compared to the 6.6L Duramax paired with a manual transmission, the automatic offered greater convenience, particularly in stop-and-go traffic, but some drivers noted a slight reduction in fuel economy.
Equipment & Trim Levels
The Silverado 3500 HD Double Cab Long Box with the Duramax engine typically came well-equipped, often falling into the LT or higher trim levels. Standard features included air conditioning, power windows and locks, a rearview camera, and a basic infotainment system. Higher trims added features like leather upholstery, heated and ventilated front seats, a premium audio system, and advanced safety technologies. Optional extras included a navigation system, a sunroof, and various towing packages. The Double Cab configuration provided comfortable seating for five passengers, with ample legroom in both rows. Interior materials were generally durable and functional, reflecting the truck’s work-oriented nature.
Chassis & Braking
The K2XX platform chassis was designed for strength and rigidity. The Silverado 3500 HD featured a fully boxed frame, contributing to its high towing and payload capacities. 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 capability. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power even when towing. An Anti-lock Braking System (ABS) was standard. The rear axle was a single rear wheel (SRW) configuration, suitable for most heavy-duty applications.
Market Reception & Comparison
The Silverado 3500 HD with the Duramax/Allison combination received generally positive reviews from automotive critics. It was praised for its powerful engine, smooth transmission, and impressive towing capabilities. Fuel economy, while not exceptional, was considered reasonable for a truck of its size and capability. Compared to competitors like the Ford Super Duty and Ram Heavy Duty, the Silverado 3500 HD was often seen as offering a good balance of performance, comfort, and value. Reliability was generally good, although some owners reported issues with the diesel particulate filter (DPF) system, a common concern with modern diesel engines.
Legacy
The 2015-2017 Chevrolet Silverado 3500 HD with the 6.6L Duramax and Allison transmission remains a popular choice in the used truck market. The Duramax LML engine is known for its longevity and relatively low maintenance costs, making these trucks a desirable option for buyers seeking a reliable and capable workhorse. While newer Silverado HD models offer more advanced technology and features, this generation represents a sweet spot in terms of value and proven durability. Well-maintained examples continue to command respectable prices, reflecting their enduring appeal and reputation for hard work.
