The Chevrolet Silverado 3500 HD III (K2XX) Crew 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 alongside a degree of comfort and refinement. It was part of the third generation of the K2XX platform, a chassis designed specifically for heavy-duty truck applications, and played a crucial role in Chevrolet’s competitive standing in the North American full-size truck market.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 3500 HD |
| Generation | Silverado 3500 HD III (K2XX) Crew 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 | 8.4 kg/Hp, 119.7 Hp/tonne |
| Weight-to-torque ratio | 3.2 kg/Nm, 312.7 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 | 29.7 l (31.38 US qt | 26.13 UK qt) |
| Kerb Weight | 3316 kg (7310.53 lbs.) |
| Max. weight | 5171 kg (11400.1 lbs.) |
| Max load | 1855 kg (4089.57 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 | 6563 mm (258.39 in.) |
| Width including mirrors | 2045 mm (80.51 in.) |
| Height | 1979 mm (77.91 in.) |
| Wheelbase | 4259 mm (167.68 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Ride height (ground clearance) | 214 mm (8.43 in.) |
| Minimum turning circle (turning diameter) | 17.1 m (56.1 ft.) |
| Drivetrain Architecture | Rear wheel drive |
| 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 |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 235/80 R17; 265/70 R18 |
| Wheel rims size | 7.5J x 17; 8J x 18 |
Powertrain & Engine Architecture
The heart of this Silverado 3500 HD variant is the Duramax LML 6.6-liter turbocharged diesel V8. This engine, a product of decades of diesel engine development by General Motors, is renowned for its durability and torque output. The LML iteration introduced several refinements over its predecessor, including a redesigned combustion chamber, improved fuel injectors, and a more efficient turbocharger. The engine utilizes a common-rail direct fuel injection system, delivering fuel at extremely high pressures for optimized combustion. The overhead valve (OHV) valvetrain, while seemingly traditional, is robust and well-suited to the demands of heavy-duty operation. The Allison 1000 six-speed automatic transmission is specifically engineered to handle the substantial torque produced by the Duramax engine. This transmission features a lock-up torque converter for improved fuel efficiency and a heavy-duty cooling system to prevent overheating under strenuous loads.
Driving Characteristics
The combination of the 397-horsepower Duramax engine and the Allison automatic transmission delivers a driving experience focused on capability rather than outright speed. While not as quick as gasoline-powered counterparts, the Silverado 3500 HD excels in situations requiring substantial pulling power. The Allison transmission is programmed for smooth, yet firm shifts, prioritizing torque delivery over rapid acceleration. The gear ratios are optimized for towing, allowing the truck to maintain speed and control even when hauling heavy loads. Compared to the 6.0-liter gasoline V8 option, the Duramax offered significantly more torque, making it the preferred choice for those regularly engaging in demanding work. Compared to higher-output Duramax variants, this 397 hp version offered a balance between power and fuel economy, making it a practical choice for everyday use alongside heavy-duty tasks.
Equipment & Trim Levels
The Crew Cab Long Box configuration provided ample interior space for passengers and cargo. Standard features typically included air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. Higher trim levels, such as the LT and High Country, added features like leather upholstery, heated and ventilated front seats, a premium audio system, navigation, and advanced safety technologies. Optional extras included a sunroof, upgraded wheels, and various towing packages. The interior design, while functional, prioritized durability and ease of use over luxury.
Chassis & Braking
The K2XX chassis is a fully boxed frame constructed from high-strength steel, providing a solid foundation for the heavy-duty truck. The front suspension utilizes an independent torsion bar setup with double wishbones, offering a comfortable ride and improved handling. The rear suspension employs a traditional leaf spring design, optimized for load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power even when heavily loaded. An Anti-lock Braking System (ABS) is standard. The rear axle configuration is Single Rear Wheel (SRW), suitable for most heavy-duty applications.
Market Reception & Comparison
The Silverado 3500 HD with the 6.6-liter Duramax and Allison automatic received generally positive reviews. Critics praised its robust powertrain, impressive towing capacity, and comfortable ride. Fuel economy, while not exceptional, was considered competitive for a truck of its size and capability. Compared to the gasoline-powered Silverado 3500 HD, the Duramax variant commanded a higher price but offered significantly lower operating costs for those logging substantial mileage. 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 Duramax LML engine and Allison transmission pairing have proven to be exceptionally durable and reliable powertrains. These trucks continue to hold their value in the used car market, particularly those that have been well-maintained. The 2015-2017 Silverado 3500 HD represents a sweet spot in the K2XX generation, offering a blend of proven technology, robust construction, and a comfortable driving experience. The LML Duramax engine remains a highly sought-after powerplant for those requiring a capable and long-lasting heavy-duty truck.
