The Chevrolet Silverado 2500HD III (K2XX) Regular Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine and a six-speed Allison automatic transmission, represents a significant iteration in Chevrolet’s heavy-duty truck lineage. Produced from 2015 to 2017, this configuration occupied a prominent position within the K2XX generation, catering to buyers requiring substantial towing and hauling capabilities without sacrificing everyday usability. This particular variant was positioned as a workhorse trim, offering a balance between capability and cost, appealing to commercial users, farmers, and individuals with demanding towing needs. It sat above the base gasoline engine options and below the more luxurious trims like the High Country.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 2500 HD |
| Generation | Silverado 2500 HD III (K2XX) Regular Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) Automatic |
| Start of production | 2015 |
| End of production | 2017 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 2 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.5 kg/Hp, 132.6 Hp/tonne |
| Weight-to-torque ratio | 2.9 kg/Nm, 346.5 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 | 2993 kg (6598.44 lbs.) |
| Max. weight | 4491 kg (9900.96 lbs.) |
| Max load | 1498 kg (3302.52 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 | 5699 mm (224.37 in.) |
| Width including mirrors | 2035 mm (80.12 in.) |
| Height | 1976 mm (77.8 in.) |
| Wheelbase | 3393 mm (133.58 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Ride height (ground clearance) | 231 mm (9.09 in.) |
| Minimum turning circle (turning diameter) | 14 m (45.93 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, 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 2500HD 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 dated compared to overhead cam designs, proved robust and reliable in heavy-duty applications. The Allison 1000 six-speed automatic transmission is specifically engineered to handle the immense 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 6.6-liter Duramax in this configuration delivers a substantial 397 horsepower and a massive 765 lb-ft of torque. While not as quick accelerating as gasoline-powered trucks, the Silverado 2500HD excels in towing and hauling. The Allison transmission is well-tuned for this engine, providing smooth and confident shifts. The gear ratios are optimized for pulling heavy loads, with a relatively low first gear for maximizing pulling power. Compared to the 6.0-liter gasoline V8 option, the Duramax offers significantly more torque at lower RPMs, making it ideal for towing large trailers or hauling heavy payloads. The automatic transmission, while convenient, does result in a slight reduction in fuel economy compared to the available manual transmission, but the trade-off in ease of use is often preferred by many drivers.
Equipment & Trim Levels
The Regular Cab Long Box configuration typically came with a relatively basic level of equipment, focusing on functionality over luxury. Standard features included air conditioning, a basic audio system, vinyl upholstery, and manual windows and locks. However, options were available to upgrade the interior, including cloth or leather upholstery, power windows and locks, a premium audio system, and a navigation system. The work truck (WT) trim was the most common for this powertrain, prioritizing affordability and durability. Higher trims, like the LT, added more comfort and convenience features.
Chassis & Braking
The K2XX chassis is a fully boxed frame designed for strength and rigidity. The front suspension utilizes an independent torsion bar setup with double wishbones, providing a comfortable ride even when the truck is unloaded. The rear suspension employs a traditional leaf spring setup, optimized for handling heavy loads. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) is standard. Due to the truck’s weight, rear brakes were often smaller than the front brakes.
Market Reception & Comparison
The Silverado 2500HD with the Duramax diesel and Allison automatic was generally well-received by critics and consumers alike. It was praised for its robust powertrain, impressive towing capacity, and comfortable ride. Compared to competitors like the Ford Super Duty and Ram 2500, the Silverado offered a competitive combination of performance, features, and price. Fuel economy, while not exceptional, was respectable for a heavy-duty truck. Reliability was generally good, although some owners reported issues with the diesel particulate filter (DPF) system.
Legacy
The Duramax LML engine paired with the Allison transmission has proven to be a remarkably durable and reliable powertrain. These trucks continue to hold their value in the used car market, particularly those that have been well-maintained. The LML Duramax is known for its longevity, and with proper maintenance, many examples are still providing years of service. The K2XX generation Silverado 2500HD remains a popular choice for those seeking a capable and dependable heavy-duty truck, and the 6.6-liter Duramax/Allison combination is considered one of the best in its class.
