The GMC Sierra 3500HD IV (GMTK2XX) Crew Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 445 horsepower and paired with a six-speed Allison automatic transmission, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2017 to 2019, this variant occupied the upper echelon of the Sierra 3500HD lineup, catering to buyers requiring substantial towing and hauling capabilities. It was part of the fourth generation (GMTK2XX) of the Sierra/Silverado HD platform, known for its increased strength and refinement compared to its predecessors.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Crew Cab Long Box |
| Type (Engine) | 6.6 TD V8 (445 Hp) 4WD DRW Automatic |
| Start of production | 2017 |
| End of production | 2019 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8.2 kg/Hp, 121.6 Hp/tonne |
| Weight-to-torque ratio | 3 kg/Nm, 337.1 Nm/tonne |
| Power | 445 Hp @ 2800 rpm |
| Power per litre | 67.4 Hp/l |
| Torque | 1234 Nm @ 1600 rpm (910.15 lb.-ft. @ 1600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Duramax L5P |
| Engine displacement | 6604 cm3 (403 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 | 3661 kg (8071.12 lbs.) |
| Max. weight | 5908 kg (13024.91 lbs.) |
| Max load | 2247 kg (4953.79 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%) | 9072 kg (20000.34 lbs.) |
| Length | 6563 mm (258.39 in.) |
| Width including mirrors | 2438 mm (95.98 in.) |
| Height | 1975 mm (77.76 in.) |
| Wheelbase | 4259 mm (167.68 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1906 mm (75.04 in.) |
| Minimum turning circle (turning diameter) | 17 m (55.77 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 | Coil spring, Double wishbone, Transverse stabilizer |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 355×40 mm |
| Rear brakes | Ventilated discs, 355×40 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 |
INTRODUCTION
The 2017-2019 GMC Sierra 3500HD Crew Cab Long Box with the 6.6L Duramax diesel and Allison automatic transmission was designed for serious work. Positioned as a premium offering within the Sierra 3500HD range, it catered to customers needing maximum capability for towing large trailers, hauling heavy loads, and demanding a comfortable, well-equipped cabin. The “DRW” designation indicates a Dual Rear Wheel configuration, further enhancing stability and payload capacity. This truck built upon the foundation of the GMTK2XX platform, which emphasized a stronger frame and improved ride quality compared to previous generations.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the Duramax L5P 6.6-liter turbocharged diesel V8. This engine is a testament to modern diesel technology, featuring a cast iron block, aluminum cylinder heads, and a robust rotating assembly. The L5P utilizes a Bosch common rail fuel injection system, delivering fuel at extremely high pressures for optimized combustion. The turbocharger, coupled with an intercooler, provides increased air density for enhanced power output. The engine’s OHV valvetrain contributes to its durability and low-end torque characteristics. The Allison 1000 Series 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 demanding conditions. The transmission’s gear ratios are optimized for both towing and everyday driving, providing a balance of power and efficiency.
Driving Characteristics
The combination of the 445 horsepower and 910 lb-ft of torque delivered by the Duramax engine and Allison transmission results in a driving experience focused on effortless power. Acceleration, while not sporty, is strong and confident, even when heavily loaded. The Allison transmission shifts smoothly and decisively, providing seamless power delivery. Compared to the 6.0L gasoline V8 option, the Duramax diesel offers significantly more torque at lower RPMs, making it ideal for towing. While the gasoline engine might feel more responsive in certain situations, the diesel’s superior torque output makes it the clear choice for demanding tasks. Compared to other diesel variants within the Sierra 3500HD lineup, such as those with slightly lower horsepower ratings, this 445 hp version provides a noticeable performance advantage, particularly when climbing hills or accelerating with a heavy load. The DRW configuration contributes to a more stable and controlled ride, especially when towing.
Equipment & Trim Levels
The Crew Cab Long Box configuration offered a spacious interior with seating for five passengers. Standard features typically included air conditioning, power windows and locks, a rearview camera, and a basic infotainment system. Higher trim levels, such as the Denali, added premium features like leather upholstery, heated and ventilated front seats, a premium sound system, and advanced safety technologies. Optional extras included a sunroof, navigation system, and various towing packages. The interior design focused on functionality and durability, with comfortable seating and easy-to-use controls. The long box bed provided ample cargo space for hauling various materials.
Chassis & Braking
The Sierra 3500HD’s chassis is built around a fully boxed, high-strength steel frame designed to withstand heavy loads and demanding conditions. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs a rigid axle with leaf springs. This setup provides a comfortable ride while maintaining excellent load-carrying capacity. The braking system features ventilated discs on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) is standard, enhancing safety and control during emergency braking situations. The DRW configuration significantly increases braking capacity and stability.
Market Reception & Comparison
The GMC Sierra 3500HD with the Duramax diesel and Allison transmission was generally well-received by critics and consumers alike. It was praised for its powerful engine, smooth transmission, comfortable ride, and impressive towing and hauling capabilities. Fuel economy, while not exceptional, was considered reasonable for a heavy-duty truck of its size and capability. Compared to competitors like the Ford Super Duty and Ram 3500, the Sierra 3500HD offered a compelling combination of performance, comfort, and features. Reliability was generally good, although diesel engines can be more expensive to maintain than gasoline engines due to the complexity of their emissions systems.
Legacy
The Duramax L5P engine and Allison transmission pairing has proven to be exceptionally durable and reliable. These trucks continue to hold their value well in the used car market, particularly those that have been well-maintained. The GMTK2XX platform represented a significant step forward in heavy-duty truck design, and the 2017-2019 Sierra 3500HD remains a popular choice for buyers seeking a capable and reliable work truck. The L5P Duramax engine is still in production today, albeit with further refinements, demonstrating its enduring legacy.
