The GMC Sierra 3500HD III, specifically the Extended Cab Long Box configuration paired with the 6.0-liter V8 engine and automatic transmission, represents a notable evolution in GMC’s heavy-duty truck lineage. Produced from 2011 to 2013 as part of the GMT900 platform’s refresh, this variant catered to buyers requiring substantial towing and hauling capabilities without entirely sacrificing interior space and comfort. It occupied a middle ground within the 3500HD lineup, balancing the practicality of standard cab models with the added luxury of crew cab versions. This truck was a staple in the American work truck market, designed for commercial applications, agricultural tasks, and demanding personal use.
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) SRW 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 | 7.9 kg/Hp, 126.8 Hp/tonne |
| Weight-to-torque ratio | 5.5 kg/Nm, 181.5 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 | 2838 kg, 6256.72 lbs. |
| Max. weight | 4854 kg, 10701.24 lbs. |
| Max load | 2016 kg, 4444.52 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%) | 5897 kg, 13000.66 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 | 1709 mm, 67.28 in. |
| Ride height (ground clearance) | 221 mm, 8.7 in. |
| Minimum turning circle (turning diameter) | 15.8 m, 51.84 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 |
| Wheel rims size | 6.5J x 17; 8J x 18 |
Powertrain & Engine Architecture
The core of this Sierra 3500HD variant is the Vortec L96 engine, a 6.0-liter (364 cubic inches) V8. This engine belongs to the Vortec family, recognized for its robust construction and relatively straightforward design. The L96 features a cast iron block and aluminum cylinder heads, enhancing its durability. It boasts a 9.6:1 compression ratio and utilizes multi-port fuel injection for precise fuel delivery. The overhead valve (OHV) valvetrain, while less advanced than overhead cam designs, is known for its reliability and ease of maintenance. Variable valve timing (VVT) was incorporated to improve fuel efficiency and low-end torque. The engine is mounted longitudinally within the chassis, powering the rear wheels. Working in conjunction with the L96 is the Hydra-Matic 6L80E six-speed automatic transmission. This transmission offered smoother shifts and improved fuel economy compared to older four-speed automatics. The 6L80E is electronically controlled, adjusting shift points based on driving conditions and throttle input.
Driving Characteristics
The 360 horsepower and 380 lb-ft of torque generated by the L96 engine, channeled through the 6L80E automatic, delivered adequate, though not thrilling, performance. Acceleration was sufficient for everyday driving and hauling moderate loads. However, when compared to the available Duramax diesel engine options, the L96 felt less powerful, particularly when towing near the truck’s maximum capacity. The automatic transmission’s gear ratios were optimized for towing and hauling, with a relatively low first gear for quick starts with heavy loads. The transmission generally shifted smoothly, but could occasionally feel hesitant during rapid downshifts. The extended cab configuration added interior space, but also increased the truck’s overall weight, slightly impacting fuel economy and handling.
Equipment & Trim Levels
The 2011-2013 Sierra 3500HD Extended Cab with the 6.0L V8 typically included standard features such as air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. The extended cab provided additional rear seating, though it was best suited for occasional passengers. Optional extras encompassed upgraded audio systems, leather upholstery, power-adjustable seats, a navigation system, and various towing packages. Trim levels varied, generally including Work Truck (WT), LT, and LTZ. The WT trim was the most basic, geared towards commercial users. The LT trim added more comfort and convenience features, while the LTZ offered the highest level of luxury and refinement.
Chassis & Braking
The Sierra 3500HD’s chassis was engineered for heavy-duty work. It featured a fully boxed frame for increased rigidity and strength. The front suspension utilized an independent torsion bar setup with double wishbone components, providing a comfortable ride while maintaining good handling. The rear suspension employed a traditional leaf spring design, optimized for load-carrying capacity. Braking was provided by ventilated disc brakes on all four wheels, offering ample stopping power even with heavy loads. An Anti-lock Braking System (ABS) was standard. Steering was accomplished via a recirculating ball steering system, which offered good feedback but could feel somewhat imprecise compared to more modern rack-and-pinion systems.
Market Reception & Comparison
Critics generally regarded the 6.0L V8-powered Sierra 3500HD as a capable work truck, but frequently highlighted the Duramax diesel engine as the superior choice for serious towing and hauling. The gasoline engine offered a lower initial cost, but its fuel economy was considerably worse than the diesel, especially under load. Compared to the 6.6L Duramax, the L96 lacked the low-end torque and overall power needed for demanding tasks. However, the L96 was generally considered more reliable and less expensive to maintain than the Duramax. The 6L80E automatic transmission was praised for its smoothness and responsiveness.
Legacy
The GMC Sierra 3500HD III with the 6.0L V8 and automatic transmission remains a common sight in the used car market today. The L96 engine is known for its durability and longevity, and with proper maintenance, can reliably exceed 200,000 miles. While not as sought after as the diesel-powered models, these trucks offer a more affordable entry point into the heavy-duty truck segment. They are often favored by buyers who prioritize simplicity, reliability, and lower maintenance costs over ultimate towing capacity and fuel efficiency. The 6L80E transmission has also proven to be a durable and reliable unit, contributing to the overall longevity of these trucks.
