The GMC Sierra 3500HD IV (GMTK2XX) Regular Cab Long Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 445 horsepower, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2017 to 2019, this configuration was part of the fourth generation of the Sierra 3500HD, known internally as the GMTK2XX platform. This model catered to buyers needing substantial towing and hauling capabilities, particularly in demanding work applications, and was a mainstay in the American truck market.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Regular Cab Long Box |
| Type (Engine) | 6.6 Duramax 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 | 2 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 7.6 kg/Hp, 131.1 Hp/tonne |
| Weight-to-torque ratio | 2.8 kg/Nm, 363.6 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 | 3394 kg (7482.49 lbs.) |
| Max. weight | 5908 kg (13024.91 lbs.) |
| Max load | 2514 kg (5542.42 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 | 5699 mm (224.37 in.) |
| Width including mirrors | 2438 mm (95.98 in.) |
| Height | 1967 mm (77.44 in.) |
| Wheelbase | 3393 mm (133.58 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1906 mm (75.04 in.) |
| Minimum turning circle (turning diameter) | 14 m (45.93 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 |
Powertrain & Engine Architecture
The heart of this Sierra 3500HD is the Duramax L5P 6.6-liter turbocharged diesel V8. This engine is a significant evolution of the Duramax design, featuring a cast iron block, aluminum cylinder heads, and a robust rotating assembly. The L5P utilizes a common-rail direct fuel injection system, delivering fuel at extremely high pressures for optimized combustion. The engine produces 445 horsepower at 2800 rpm and a massive 910 lb-ft (1234 Nm) of torque at 1600 rpm. This torque output is crucial for heavy towing and hauling. The engine features an overhead valve (OHV) valvetrain, a design choice prioritizing durability and low-end torque. The Allison 1000 six-speed automatic transmission is paired with the Duramax engine. This transmission is renowned for its durability and ability to handle high torque loads. It features electronically controlled shifts and a lock-up torque converter for improved fuel efficiency.
Driving Characteristics
The 445 hp/910 lb-ft combination delivers impressive performance, even with the substantial weight of the truck. While not designed for outright speed, the Sierra 3500HD offers strong acceleration and effortless cruising. The Allison transmission is well-matched to the engine, providing smooth and predictable shifts. The gear ratios are optimized for towing, allowing the truck to maintain speed and control even when hauling heavy loads. Compared to lower-output versions of the Sierra 3500HD, this variant provides a noticeable increase in power and responsiveness. Manual transmission equipped models offered a more engaging driving experience, but the automatic provides convenience and ease of use, particularly in stop-and-go traffic or when towing.
Equipment & Trim Levels
The Regular Cab Long Box configuration typically served as a work-oriented trim. Standard features included air conditioning, a basic audio system, vinyl upholstery, and manual windows and locks. However, options were plentiful. Buyers could add features like power windows and locks, upgraded audio systems, leather upholstery, and a navigation system. The interior was functional and durable, designed to withstand the rigors of daily use. The Long Box bed provided ample cargo space, making it ideal for hauling materials and equipment.
Chassis & Braking
The Sierra 3500HD features a heavy-duty chassis designed to withstand significant loads. The front suspension utilizes coil springs and a double wishbone design, while the rear suspension employs leaf springs. This setup provides a comfortable ride while maintaining excellent stability and load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) is standard. The dual rear wheel (DRW) configuration of this specific model further enhances stability and load capacity.
Market Reception & Comparison
The 6.6-liter Duramax diesel engine was consistently praised for its power, torque, and reliability. Critics noted the Sierra 3500HD’s robust construction and impressive towing capabilities. Compared to gasoline-powered versions of the Sierra 3500HD, the diesel offered significantly better fuel economy when towing heavy loads. However, the diesel engine carried a higher price tag. Compared to competitors like the Ford Super Duty and Ram 3500, the Sierra 3500HD was generally considered to be a strong contender, offering a compelling combination of performance, reliability, and features.
Legacy
The Duramax L5P engine has proven to be exceptionally durable, with many examples exceeding 200,000 miles with proper maintenance. The Allison transmission is equally reliable. On the used car market, these trucks hold their value well, particularly those in good condition with well-documented maintenance histories. The 2017-2019 Sierra 3500HD with the Duramax diesel and Allison automatic remains a popular choice for buyers seeking a capable and reliable heavy-duty pickup truck. Regular maintenance, including oil changes and fuel filter replacements, is crucial for ensuring the longevity of this powertrain.
