The GMC Sierra 3500HD III, specifically the Extended Cab Long Box configuration with the 6.0-liter V8 engine and automatic transmission, represents a significant iteration in GMC’s heavy-duty truck lineage. Produced from 2011 to 2013 as part of the GMT900 platform’s facelift, this variant was designed to cater to owners requiring substantial towing and hauling capabilities without sacrificing everyday usability. It occupied a sweet spot in the Sierra 3500HD lineup, offering a balance between power, comfort, and cost, positioned above the base models but below the more specialized or diesel-powered trims.
Technical Specifications
| Brand | GMC |
| Model | Sierra 3500HD |
| Generation | Sierra 3500HD III (GMT900, facelift 2011) Extended Cab Long Box |
| Type (Engine) | 6.0 V8 (360 Hp) DRW Automatic |
| Start of production | 2011 |
| End of production | 2013 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 2 |
| Fuel Type | Petrol (Gasoline) |
| Weight-to-power ratio | 8.4 kg/Hp, 118.9 Hp/tonne |
| Weight-to-torque ratio | 5.9 kg/Nm, 170.1 Nm/tonne |
| Power | 360 Hp @ 5400 rpm |
| Power per litre | 60.3 Hp/l |
| Torque | 515 Nm @ 4200 rpm, 379.84 lb.-ft. @ 4200 rpm |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | Vortec L96 |
| Engine displacement | 5967 cm3, 364.13 cu. in. |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 101.6 mm, 4 in. |
| Piston Stroke | 92 mm, 3.62 in. |
| Compression ratio | 9.6:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV, VVT |
| Engine oil capacity | 5.7 l, 6.02 US qt | 5.02 UK qt |
| Coolant | 15.5 l, 16.38 US qt | 13.64 UK qt |
| Kerb Weight | 3028 kg, 6675.6 lbs. |
| Max. weight | 5908 kg, 13024.91 lbs. |
| Max load | 2880 kg, 6349.31 lbs. |
| Trunk (boot) space – maximum | 2138 l, 75.5 cu. ft. |
| Fuel tank capacity | 136 l, 35.93 US gal | 29.92 UK gal |
| Permitted trailer load with brakes (12%) | 6169 kg, 13600.32 lbs. |
| Length | 6337 mm, 249.49 in. |
| Width including mirrors | 2436 mm, 95.91 in. |
| Height | 1966 mm, 77.4 in. |
| Wheelbase | 4018 mm, 158.19 in. |
| Front track | 1748 mm, 68.82 in. |
| Rear (Back) track | 1906 mm, 75.04 in. |
| Ride height (ground clearance) | 213 mm, 8.39 in. |
| Minimum turning circle (turning diameter) | 16.1 m, 52.82 ft. |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission Hydra-Matic |
| 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, 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 |
INTRODUCTION
The 2011-2013 GMC Sierra 3500HD Extended Cab Long Box, powered by the 6.0-liter Vortec L96 V8 and paired with a six-speed Hydra-Matic automatic transmission, was a workhorse designed for demanding tasks. This configuration built upon the GMT900 platform, a fully-boxed frame designed for increased strength and stability. The facelift introduced in 2011 brought revised styling, improved interior materials, and enhanced features compared to the earlier GMT900 models. The Extended Cab provided additional passenger space compared to the regular cab, while the Long Box offered a substantial cargo bed for hauling. This particular trim level aimed to provide a balance between capability and affordability, making it a popular choice for both commercial and personal use.
Powertrain & Engine Architecture
At the heart of this Sierra 3500HD lies the Vortec L96 6.0-liter V8 engine. This engine is a member of the Vortec family, known for its robust construction and reliable performance. The L96 features a cast iron block and aluminum cylinder heads, utilizing a 9.6:1 compression ratio and a multi-port fuel injection system. The overhead valve (OHV) valvetrain, coupled with variable valve timing (VVT), helps optimize power delivery and fuel efficiency. The engine produces 360 horsepower at 5400 rpm and 515 lb-ft of torque at 4200 rpm. The Hydra-Matic 6L80E six-speed automatic transmission was specifically chosen for its durability and ability to handle the engine’s substantial torque output. This transmission features electronically controlled shifting and overdrive for improved fuel economy at highway speeds. The rear-wheel-drive configuration was standard, providing a traditional truck driving experience.
Driving Characteristics
The 6.0-liter V8 and six-speed automatic combination delivered a capable, though not exceptionally quick, driving experience. The emphasis was clearly on torque, making it well-suited for towing and hauling heavy loads. Acceleration was adequate for everyday driving, but the truck’s substantial weight (over 6,600 lbs) limited its responsiveness. The automatic transmission provided smooth shifts, and the gear ratios were optimized for both low-end grunt and highway cruising. Compared to the available Duramax diesel engine, the 6.0-liter V8 offered less torque and lower fuel economy, but it was significantly less expensive to purchase and maintain. Manual transmission options were available on other Sierra 3500HD trims, offering more driver control, but the automatic was favored by many for its ease of use, especially when towing.
Equipment & Trim Levels
The Extended Cab Long Box 6.0L Automatic trim typically included standard features such as air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. The interior was functional and durable, designed to withstand the rigors of work truck use. Optional extras included upgraded audio systems, leather upholstery, power-adjustable seats, a navigation system, and various towing packages. The exterior featured a chrome grille, black bumpers, and standard headlights. The Long Box provided a generous cargo bed length, ideal for hauling large items. The overall trim level aimed for a balance between functionality and comfort, appealing to buyers who needed a capable truck without the luxury features of higher-end trims.
Chassis & Braking
The Sierra 3500HD’s chassis was built around a fully-boxed frame, providing a solid foundation for heavy-duty use. The front suspension utilized an independent torsion bar and double wishbone setup, while the rear suspension employed a traditional leaf spring configuration. This setup prioritized load-carrying capacity and stability. Braking duties were handled by ventilated disc brakes on all four wheels, with ABS (Anti-lock Braking System) as standard equipment. The front brakes measured 355x40mm, while the rear brakes were 373x34mm. The steering system was a cone worm with recirculation balls, providing a robust and reliable steering feel.
Market Reception & Comparison
The 2011-2013 GMC Sierra 3500HD with the 6.0-liter V8 and automatic transmission received generally positive reviews. Critics praised its robust construction, ample towing capacity, and comfortable ride. However, the fuel economy was often cited as a drawback compared to diesel-powered competitors. Compared to the Duramax diesel option, the 6.0-liter V8 was significantly more affordable to purchase, but it offered less torque and lower fuel efficiency. The gasoline engine also required less expensive maintenance, as diesel engines typically have more complex and costly maintenance requirements. The 6.0-liter V8 was a popular choice for buyers who prioritized initial cost and simplicity over ultimate towing performance and fuel economy.
Legacy
The Vortec L96 6.0-liter V8, paired with the 6L80E automatic transmission, has proven to be a relatively reliable powertrain combination. While not without its potential issues (such as Active Fuel Management system problems in some cases), the engine is generally considered durable and capable. In the used car market, these Sierra 3500HDs remain popular choices for buyers seeking a capable and affordable heavy-duty truck. Their relatively simple design and readily available parts contribute to their continued appeal. However, potential buyers should be aware of the engine’s fuel consumption and the importance of regular maintenance to ensure long-term reliability.
