The GMC Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box, equipped with the 6.6-liter Duramax Turbo Diesel V8 engine producing 397 horsepower and paired with a 4WD SRW Automatic transmission, was a key offering in GMC’s heavy-duty truck lineup from 2015 to 2017. This variant represented a balance between capability and everyday usability, targeting customers needing serious towing and hauling capacity without sacrificing passenger comfort. It sat within the fourth generation of the Sierra 3500HD, known as the GMTK2XX platform, which brought significant improvements in interior refinement, technology, and overall robustness compared to its predecessors.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD IV (GMTK2XX) Crew Cab Standard Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) 4WD SRW 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 | 8.4 kg/Hp, 118.4 Hp/tonne |
| Weight-to-torque ratio | 3.2 kg/Nm, 309.2 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 | 3354 kg (7394.3 lbs.) |
| Max. weight | 5216 kg (11499.31 lbs.) |
| Max load | 1862 kg (4105.01 lbs.) |
| Trunk (boot) space – maximum | 1728 l (61.02 cu. ft.) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 5897 kg (13000.66 lbs.) |
| Length | 6083 mm (239.49 in.) |
| Width including mirrors | 2045 mm (80.51 in.) |
| Height | 1985 mm (78.15 in.) |
| Wheelbase | 3904 mm (153.7 in.) |
| Front track | 1748 mm (68.82 in.) |
| Rear (Back) track | 1709 mm (67.28 in.) |
| Minimum turning circle (turning diameter) | 15.8 m (51.84 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, 373×34 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 variant is the Duramax LML 6.6-liter turbocharged diesel V8. This engine, a staple of GMC’s heavy-duty trucks, is renowned for its durability and substantial torque output. The LML iteration introduced several refinements over previous Duramax engines, including a redesigned combustion chamber, improved fuel injectors, and a more efficient turbocharger. The engine utilizes a diesel commonrail fuel injection system, delivering highly pressurized fuel directly into the cylinders for optimal combustion. The overhead valve (OHV) valvetrain, while traditional, proved reliable and contributed to the engine’s low-end torque characteristics. The Allison 6-speed automatic transmission is specifically tuned to handle the immense torque produced by the Duramax engine. It features a lock-up torque converter for improved fuel efficiency at highway speeds and robust internal components to withstand the demands of heavy towing and hauling.
Driving Characteristics
The 397 horsepower and 764.85 lb-ft of torque delivered by this combination provided substantial pulling power. While not as quick accelerating as gasoline-powered trucks or higher-output diesel variants, the Sierra 3500HD with this powertrain excelled at towing and hauling heavy loads. The Allison transmission’s gear ratios were optimized for maximizing torque delivery, making it easy to maintain control even when fully loaded. Compared to the 6.0L gasoline V8 option, the Duramax offered significantly more torque and better fuel economy when towing. Compared to the higher-output Duramax variants (typically around 400 hp), this 397 hp version offered a slightly more relaxed driving experience, prioritizing fuel efficiency and longevity over outright performance. The automatic transmission, while convenient, didn’t offer the same level of control as a manual transmission, particularly when descending steep grades with a heavy load.
Equipment & Trim Levels
The Crew Cab configuration offered spacious seating for five passengers, making it suitable for both work and family use. Standard features typically included air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. The Standard Box (short bed) provided a practical cargo area. Optional extras included leather upholstery, a premium audio system, navigation, a rear-seat entertainment system, and various towing packages. Trim levels above the base model added features like chrome exterior accents, upgraded interior materials, and additional convenience features.
Chassis & Braking
The Sierra 3500HD featured a robust chassis designed to withstand the stresses of heavy-duty use. The front suspension utilized coil springs and a double wishbone design, while the rear suspension employed a traditional leaf spring setup. This configuration provided a comfortable ride while maintaining excellent load-carrying capacity. Braking duties were handled by ventilated disc brakes on all four wheels, providing ample stopping power even when towing. An Anti-lock Braking System (ABS) was standard. The rear axle was a single rear wheel (SRW) configuration, common for this class of truck.
Market Reception & Comparison
The GMC Sierra 3500HD with the 6.6-liter Duramax and Allison automatic transmission was generally well-received by critics and consumers alike. It was praised for its powerful engine, smooth-shifting transmission, and comfortable ride. Fuel economy, while not exceptional, was competitive for a heavy-duty truck. Compared to Ford’s Super Duty and Ram’s heavy-duty offerings, the Sierra 3500HD was often seen as offering a good balance of capability, comfort, and refinement. 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 Duramax LML engine and Allison transmission combination proved to be exceptionally durable, and many examples of this powertrain are still in service today. The GMTK2XX platform Sierra 3500HDs hold their value reasonably well, particularly those in good condition with well-documented maintenance histories. The 397 hp/automatic configuration remains a popular choice in the used truck market, appealing to buyers seeking a capable and reliable heavy-duty truck without the higher price tag of more powerful variants. The LML Duramax engine is considered one of the most reliable diesel engines ever produced, and its longevity contributes to the continued desirability of these trucks.
