The Chevrolet Silverado 2500HD III (K2XX) Crew Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 397 horsepower and paired with a 6-speed Allison automatic transmission, represents a significant iteration in Chevrolet’s heavy-duty truck lineage. Produced from 2015 to 2017, this configuration occupied a premium position within the Silverado 2500HD lineup, targeting buyers requiring substantial towing and hauling capabilities alongside a degree of refinement. It was part of the third generation of the K2XX platform, known for its increased strength and improved ride quality compared to its predecessors.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 2500 HD |
| Generation | Silverado 2500 HD III (K2XX) Crew Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) 4WD 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 | 8.6 kg/Hp, 115.9 Hp/tonne |
| Weight-to-torque ratio | 3.3 kg/Nm, 302.8 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 | 3425 kg (7550.83 lbs.) |
| Max. weight | 4536 kg (10000.17 lbs.) |
| Max load | 1111 kg (2449.34 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 | 1980 mm (77.95 in.) |
| Wheelbase | 4258 mm (167.64 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Ride height (ground clearance) | 208 mm (8.19 in.) |
| Minimum turning circle (turning diameter) | 17.1 m (56.1 ft.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| 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, 350×40 mm |
| Rear brakes | Ventilated discs, 360×34 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Tires size | 245/75 R17; 265/70 R17; 265/70 R18; 265/60 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
Powertrain & Engine Architecture
The heart of this Silverado variant is the Duramax LML 6.6-liter turbocharged diesel V8. This engine represents a refinement of the previous LBZ and LMM Duramax engines, incorporating a redesigned combustion chamber, improved fuel injection system, and a more efficient turbocharger. The LML utilizes a common-rail direct injection system, delivering fuel at extremely high pressures for optimized combustion. The engine features an overhead valve (OHV) valvetrain, a design choice favored for its durability and low-end torque characteristics. The turbocharger, coupled with an intercooler, provides increased air density for enhanced power output. The Allison 1000 6-speed automatic transmission is specifically designed to handle the substantial torque produced by the Duramax engine. It features a lock-up torque converter for improved fuel efficiency and a heavy-duty cooling system to prevent overheating under demanding conditions.
Driving Characteristics
The 397 horsepower and 765 lb-ft of torque delivered by this combination translate to impressive towing and hauling capabilities. While not as overtly quick as gasoline-powered counterparts, the Duramax offers a broad, flat torque curve, making it exceptionally capable at low speeds and when carrying heavy loads. The Allison transmission is well-matched to the engine, providing smooth and decisive shifts. Compared to the 6.0L gasoline V8 option, the Duramax provides significantly more torque, making it the preferred choice for those regularly towing large trailers or hauling substantial payloads. The automatic transmission, while convenient, does result in a slight reduction in fuel economy compared to the available manual transmission options. However, the convenience and ease of use often outweigh this consideration for many drivers.
Equipment & Trim Levels
The Crew Cab Long Box configuration, combined with the Duramax engine, typically fell into the higher trim levels of the Silverado 2500HD range, such as the LTZ or High Country. Standard features included air conditioning, power windows and locks, a premium audio system, and a rearview camera. Higher trims added leather upholstery, heated and ventilated front seats, a navigation system, and advanced safety features. Optional extras included a sunroof, upgraded wheels, and various towing packages. The interior design focused on functionality and durability, with comfortable seating and a user-friendly layout.
Chassis & Braking
The K2XX platform features a fully boxed frame constructed from high-strength steel, providing a robust foundation for heavy-duty use. 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 configuration balances ride comfort with 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 ratios varied depending on the specific configuration, influencing both towing capacity and fuel economy.
Market Reception & Comparison
The Duramax-equipped Silverado 2500HD was consistently praised by automotive critics for its exceptional towing and hauling capabilities, as well as its refined driving experience compared to older heavy-duty trucks. Fuel economy, while not a primary concern for buyers in this segment, was generally considered competitive with other diesel-powered trucks. Compared to the gasoline-powered Silverado 2500HD, the Duramax offered significantly more torque and a lower cost of ownership for high-mileage users. 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 Silverado 2500HD with the 6.6L Duramax and Allison automatic remains a popular choice in the used truck market. The LML Duramax engine is known for its durability and longevity, and well-maintained examples can provide many years of reliable service. The combination of power, capability, and relative refinement has made this truck a favorite among those requiring a heavy-duty workhorse. While newer Silverado 2500HD models offer updated technology and features, this generation represents a sweet spot for value and proven performance.
