The GMC Sierra 3500HD, specifically the 2024 model year facelift in Double Cab Long Bed configuration with the 6.6-liter V8 engine producing 401 horsepower, represents GMC’s heavy-duty full-size pickup truck offering. Introduced as part of the GMTT1XX generation, this variant caters to buyers needing substantial towing and payload capacity, blending work-truck durability with a degree of refinement. The 2024 refresh brought updated styling and technology, solidifying the Sierra 3500HD’s position as a competitor to Ford’s Super Duty and Ram’s heavy-duty offerings. This particular configuration, with its dual rear wheels (DRW), is geared towards those requiring maximum stability and hauling capability.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD V (GMTT1XX, facelift 2024) Double Cab Long Bed |
| Type (Engine) | 6.6 V8 (401 Hp) 4WD DRW Automatic |
| Start of production | 2024 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 8.5 kg/Hp, 117.4 Hp/tonne |
| Weight-to-torque ratio | 5.4 kg/Nm, 184.1 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 |
| Engine oil capacity | 7.6 l (8.03 US qt | 6.69 UK qt) |
| Coolant capacity | 14.6 l (15.43 US qt | 12.85 UK qt) |
| Kerb Weight | 3417 kg (7533.2 lbs) |
| Max. weight | 6350 kg (13999.35 lbs) |
| Max load | 2933 kg (6466.16 lbs) |
| Fuel tank capacity | 136 l (35.93 US gal | 29.92 UK gal) |
| Permitted trailer load with brakes (12%) | 8164 kg (17998.54 lbs) |
| Length | 6534 mm (257.24 in) |
| Width including mirrors | 2457 mm (96.73 in) |
| Height | 2037 mm (80.2 in) |
| Wheelbase | 4127 mm (162.48 in) |
| Front track | 1731 mm (68.15 in) |
| Rear track | 1905 mm (75 in) |
| Ride height (ground clearance) | 264 mm (10.39 in) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front engaged via clutch. |
| Number of gears and type of gearbox | 10 gears, automatic transmission Allison |
| Front suspension | Independent torsion bar, double 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 |
| Power steering | Hydraulic Steering |
| Tires size | 235/80 R17; 235/80 R18 |
| Wheel rims size | 6.5J x 17; 8J x 18 |
Introduction
The 2024 GMC Sierra 3500HD Double Cab Long Bed with the 6.6L V8 and 4WD DRW configuration is a heavy-duty pickup designed for demanding tasks. Positioned within the Sierra 3500HD lineup, this variant sits towards the higher end in terms of capability, offering a substantial increase in towing and payload compared to the 2500HD models. The DRW setup (dual rear wheels) is specifically aimed at customers who frequently tow large trailers – such as fifth-wheel campers or heavy equipment – and require maximum stability. The facelifted 2024 model builds upon the established GMTT1XX platform, incorporating updated styling cues and interior enhancements.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD is the 6.6-liter L8T V8 gasoline engine. This engine utilizes direct fuel injection, a technology that improves efficiency and power output by injecting fuel directly into the combustion chamber. The engine employs an overhead valve (OHV) valvetrain, a traditional design known for its durability and relatively simple maintenance. The 10-speed Allison automatic transmission is a key component, providing a wide range of gear ratios to optimize both towing performance and fuel economy. This transmission is renowned for its robustness and smooth shifting characteristics. The engine’s naturally aspirated design, while not offering the immediate torque of a turbocharged engine, provides a linear power delivery that many drivers find predictable and controllable.
Driving Characteristics
The 401 horsepower and 463.93 lb-ft of torque delivered by the 6.6L V8, coupled with the 10-speed Allison transmission, results in a capable, though not overtly sporty, driving experience. The DRW configuration significantly enhances stability when towing, minimizing sway and providing a more confident feel. The 10-speed transmission allows the engine to operate within its optimal power band more frequently, even when hauling heavy loads. Compared to the available Duramax diesel engine option, this gasoline V8 offers quicker acceleration in lighter driving scenarios but lacks the diesel’s superior low-end torque for heavy towing. The gear ratios are tuned for maximizing towing capacity, meaning that acceleration from a standstill with a heavy load will be deliberate rather than brisk.
Equipment & Trim Levels
The Double Cab Long Bed configuration typically comes standard with features like a trailering package, including integrated trailer brake controller, and a rearview camera. Interior appointments generally include cloth upholstery, though leather options are available. Standard features also include an infotainment system with a touchscreen display, Apple CarPlay and Android Auto compatibility, and a suite of safety features. Higher trim levels, such as Denali, add premium features like leather upholstery, heated and ventilated seats, a premium sound system, and advanced driver-assistance systems. Optional extras include a power sunroof, upgraded wheels, and various appearance packages.
Chassis & Braking
The Sierra 3500HD utilizes a robust chassis designed to withstand the stresses of heavy-duty use. The front suspension features an independent torsion bar setup with double wishbones, providing a comfortable ride while maintaining stability. The rear suspension employs a traditional leaf spring design, optimized for load-carrying capacity. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power even when heavily loaded. The ABS (Anti-lock Braking System) enhances safety by preventing wheel lockup during hard braking. The DRW configuration contributes to improved braking performance by distributing the braking force over a larger contact patch.
Market Reception & Comparison
Critics generally praised the 2024 Sierra 3500HD for its strong towing capabilities, comfortable ride (considering its heavy-duty nature), and updated interior. The 6.6L V8 engine, while not as fuel-efficient as the diesel option, was noted for its smooth operation and adequate power for most tasks. Compared to the diesel variant, the gasoline engine offers a lower initial purchase price but higher long-term fuel costs, especially when towing frequently. The DRW configuration, while providing superior stability, can make maneuvering in tight spaces more challenging. Fuel economy is a compromise, averaging around 14-16 mpg in combined driving, depending on load and driving conditions.
Legacy
The GMTT1XX generation Sierra 3500HD, and specifically the 6.6L V8/Allison automatic combination, has proven to be a reliable powertrain. The Allison transmission, in particular, is known for its longevity and ability to withstand heavy use. While the gasoline engine may require more frequent maintenance than the Duramax diesel, it generally offers lower repair costs when issues do arise. On the used car market, these trucks hold their value relatively well, particularly those that have been well-maintained and haven’t been subjected to extreme abuse. The DRW configuration remains popular among those who prioritize towing capacity and stability above all else, ensuring continued demand for this specific variant.
