The GMC Sierra 3500HD IV (GMTK2XX) Crew Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 397 horsepower and paired with a 4WD Dual Rear Wheel (DRW) automatic transmission, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2015 to 2017, this variant occupied a premium position within the Sierra 3500HD lineup, targeting buyers requiring substantial towing and hauling capabilities alongside a comfortable, well-equipped cabin. It was part of the fourth generation of the Sierra/Silverado HD trucks, known as the GMTK2XX platform, which brought substantial improvements in capability, refinement, and technology.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Crew Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) 4WD DRW 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 | 9.1 kg/Hp, 109.5 Hp/tonne |
| Weight-to-torque ratio | 3.5 kg/Nm, 285.9 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 | 3627 kg (7996.17 lbs.) |
| Max. weight | 5908 kg (13024.91 lbs.) |
| Max load | 2281 kg (5028.74 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.) |
| Ride height (ground clearance) | 210 mm (8.27 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, Wishbone |
| 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 2015-2017 GMC Sierra 3500HD Crew Cab Long Box with the 6.6L Duramax diesel and Allison automatic transmission was engineered for demanding tasks. Positioned as a top-tier offering, it catered to customers needing maximum towing capacity and payload, such as those involved in construction, agriculture, or recreational activities involving large trailers. The “DRW” (Dual Rear Wheel) configuration further enhanced stability and load-carrying ability. This truck built upon the foundation of the GMTK2XX platform, which emphasized a more refined driving experience and improved interior appointments compared to previous generations.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the Duramax LML 6.6-liter turbocharged diesel V8. This engine is a testament to diesel engineering, featuring a cast iron block, aluminum cylinder heads, and a robust crankshaft. The LML iteration of the Duramax introduced a revised turbocharger, improved fuel injection system, and enhanced exhaust gas recirculation (EGR) system to meet stricter emissions standards while maintaining impressive power output. The engine utilizes a common-rail direct injection system, delivering fuel at extremely high pressures for optimal combustion. The overhead valve (OHV) valvetrain, while seemingly traditional, is known for its durability and reliability. The Allison 1000 six-speed automatic transmission is specifically designed to handle the immense 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 strenuous conditions.
Driving Characteristics
The combination of the 397 horsepower and 765 lb-ft of torque delivered by the Duramax engine, coupled with the Allison transmission, provides a commanding driving experience. While not designed for outright speed, the truck offers ample power for accelerating with a heavy load or maintaining highway speeds. The Allison transmission’s gear ratios are optimized for towing, providing smooth and confident shifts even under duress. Compared to the 6.0L gasoline V8 option, the Duramax offers significantly more torque at lower RPMs, making it ideal for pulling heavy trailers. The DRW configuration contributes to a more stable and controlled ride, especially when towing. However, the added weight and complexity of the DRW setup do result in a slightly less nimble feel compared to single rear wheel (SRW) models.
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 leather upholstery, heated and ventilated front seats, a premium sound system, and advanced safety features like lane departure warning and forward collision alert. Optional extras included a sunroof, navigation system, and a variety of towing packages tailored to specific needs. The interior design focused on functionality and durability, with robust materials and a user-friendly layout.
Chassis & Braking
The Sierra 3500HD’s chassis is built for heavy-duty applications. It features a fully boxed frame constructed from high-strength steel, providing exceptional rigidity and durability. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs a traditional leaf spring setup. The DRW configuration necessitates a wider rear track for increased stability. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power even with a heavy load. An Anti-lock Braking System (ABS) is standard, enhancing safety and control during emergency braking situations.
Market Reception & Comparison
The 2015-2017 GMC Sierra 3500HD with the Duramax diesel and Allison automatic received generally positive reviews. Critics praised its powerful engine, smooth transmission, and comfortable ride. Compared to the 6.0L gasoline engine option, the Duramax offered superior towing capacity and fuel economy, albeit at a higher initial cost. The Duramax/Allison combination was often favored over the Cummins/Aisin pairing found in the Ram 3500HD, with some reviewers citing the Allison’s smoother shifting and overall refinement. However, the Duramax engine’s complex emissions control systems were a point of concern for some, as they could potentially lead to higher maintenance costs over the long term.
Legacy
The Duramax LML engine and Allison 1000 transmission have proven to be remarkably reliable powertrains when properly maintained. These trucks continue to hold their value in the used car market, particularly those that have been well-cared for and have a documented service history. Common maintenance items include regular oil changes, fuel filter replacements, and coolant flushes. The emissions control systems, including the diesel particulate filter (DPF) and exhaust gas recirculation (EGR) system, require periodic cleaning or replacement to ensure optimal performance and compliance with emissions regulations. Overall, the 2015-2017 GMC Sierra 3500HD DRW with the Duramax diesel remains a highly capable and desirable heavy-duty truck, representing a sweet spot in terms of power, refinement, and long-term reliability.
