The GMC Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed, equipped with the 6.6-liter V8 engine producing 401 horsepower and paired with a four-wheel-drive Dual Rear Wheel (DRW) automatic transmission, represents a significant offering in the heavy-duty pickup truck segment. Produced from 2020 to 2023, this variant occupied a premium position within the Sierra 3500HD lineup, catering to buyers requiring substantial towing and payload capacity. It builds upon the foundation of the GMTT1XX platform, a robust chassis designed for demanding work applications, and aimed squarely at the North American market where heavy-duty trucks are a mainstay.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX) Crew Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 4WD DRW Automatic |
| Start of production | 2020 |
| End of production | 2023 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 9.4 kg/Hp, 106.5 Hp/tonne |
| Weight-to-torque ratio | 6 kg/Nm, 167.1 Nm/tonne |
| Power | 401 Hp @ 5200 rpm |
| Torque | 629 Nm @ 4000 rpm, 463.93 lb.-ft. @ 4000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L8T |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103.25 mm / 4.06 in. |
| Piston Stroke | 98 mm / 3.86 in. |
| Compression ratio | 10.8:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Direct injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV, VVT |
| Engine oil capacity | 7.6 l / 8.03 US qt | 6.69 UK qt |
| Coolant | 14.6 l / 15.43 US qt | 12.85 UK qt |
| Kerb Weight | 3765 kg / 8300.4 lbs. |
| Max. weight | 6350 kg / 13999.35 lbs. |
| Max load | 2585 kg / 5698.95 lbs. |
| 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 | 6759 mm / 266.1 in. |
| Width including mirrors | 2457 mm / 96.73 in. |
| Height | 2033 mm / 80.04 in. |
| Wheelbase | 4369 mm / 172.01 in. |
| Front track | 1731 mm / 68.15 in. |
| Rear (Back) track | 1905 mm / 75 in. |
| Ride height (ground clearance) | 264 mm / 10.39 in. |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels permanently, and the front wheels are driven through an electrically or mechanically operated clutch if necessary. |
| Drive wheel | All wheel drive (4×4) |
| Number of gears and type of gearbox | 6 gears, automatic transmission Hydra-Matic |
| 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 |
| Power steering | Hydraulic Steering |
| Tires size | 235/80 R17; 265/70 R17; 245/75 R17; 275/70 R18; 275/65 R20 |
| Wheel rims size | 7.5J x 17; 8J x 18; 8.5J x 20 |
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD variant lies the 6.6-liter L8T V8 gasoline engine. This engine is a naturally aspirated, overhead valve (OHV) design featuring direct fuel injection and variable valve timing (VVT). The direct injection system optimizes combustion efficiency and power delivery, while VVT enhances low-end torque and improves overall fuel economy. The engine produces 401 horsepower at 5200 rpm and 464 lb-ft of torque at 4000 rpm. The Hydra-Matic 6-speed automatic transmission is the sole transmission option for this configuration. This transmission is known for its durability and smooth shifting characteristics, crucial for handling the engine’s output and the truck’s substantial weight. The transmission is electronically controlled, adapting shift points based on driving conditions and throttle input.
Driving Characteristics
The 6.6L V8 and 6-speed automatic combination delivers a robust, if not overtly sporty, driving experience. While not as quick as lighter-duty trucks or those equipped with diesel engines, the Sierra 3500HD provides ample power for everyday driving and demanding tasks. The automatic transmission is well-tuned for towing, holding gears effectively when climbing hills or hauling heavy loads. The DRW configuration significantly enhances stability when towing, distributing weight more evenly across the rear axle. Compared to the available Duramax diesel engine, this gasoline variant offers a lower initial purchase price but sacrifices fuel economy and ultimate towing capacity. The gear ratios are optimized for torque multiplication, prioritizing pulling power over rapid acceleration.
Equipment & Trim Levels
The Crew Cab Long Bed configuration is a well-equipped trim, typically including features like a premium infotainment system with touchscreen display, Apple CarPlay and Android Auto compatibility, and a comprehensive suite of safety technologies. Standard interior appointments include cloth upholstery, though leather options were readily available. Optional extras included a power sunroof, heated and ventilated front seats, a premium audio system, and advanced driver-assistance features such as adaptive cruise control and lane departure warning. The long bed provides ample cargo space, making it suitable for both work and recreational use.
Chassis & Braking
The GMTT1XX platform features a fully boxed frame constructed from high-strength steel, providing a solid foundation for the truck’s substantial weight and payload capacity. The front suspension utilizes a coil spring, double wishbone design with a transverse stabilizer bar, while the rear suspension employs a traditional leaf spring setup. This configuration balances ride comfort with load-carrying capability. Braking duties are handled by ventilated disc brakes at all four corners, measuring 355x40mm. An Anti-lock Braking System (ABS) is standard, enhancing braking performance and stability. The hydraulic power steering provides responsive and predictable handling.
Market Reception & Comparison
The GMC Sierra 3500HD with the 6.6L V8 and automatic transmission received generally positive reviews, particularly from buyers prioritizing affordability and simplicity over maximum towing capacity. Critics noted the engine’s adequate power for most tasks, but acknowledged that the Duramax diesel offered superior performance and fuel economy. Fuel economy figures typically ranged around 15-17 mpg in combined driving. Compared to competitors like the Ford Super Duty and Ram 3500, the Sierra 3500HD offered a competitive combination of features, capability, and price.
Legacy
The L8T 6.6L V8 engine, while not as renowned for longevity as the Duramax diesel, has proven to be a relatively reliable powertrain when properly maintained. Common maintenance items include regular oil changes, coolant flushes, and spark plug replacements. In the used car market, these Sierra 3500HD models represent a good value for buyers seeking a capable and affordable heavy-duty truck. The DRW configuration, combined with the robust chassis, ensures these trucks remain capable workhorses for years to come. However, potential buyers should be aware of the higher fuel consumption compared to diesel alternatives and inspect the truck thoroughly for signs of heavy use or abuse.
