The Chevrolet Silverado 3500 HD II, specifically the Extended Cab Long Box configuration with the 6.6-liter Duramax Turbo Diesel V8 engine and Allison automatic transmission, represents a significant iteration in Chevrolet’s heavy-duty truck lineage. Produced from 2011 to 2014, this variant falls within the GMT900 platform’s facelifted generation, offering a blend of robust capability, improved refinement, and diesel-specific features aimed at the demanding needs of commercial users and serious towing enthusiasts. This particular trim level occupied a premium position within the Silverado 3500 HD lineup, offering a substantial step up in performance and towing capacity compared to gasoline-powered options.
Technical Specifications
| Brand | Chevrolet |
| Model | Silverado 3500 HD |
| Generation | Silverado 3500 HD II (GMT900, facelift 2011) Extended Cab Long Box |
| Type (Engine) | 6.6 Duramax TD V8 (397 Hp) DRW Automatic |
| Start of production | 2011 |
| End of production | 2014 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 2 |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8.5 kg/Hp, 118 Hp/tonne |
| Weight-to-torque ratio | 3.2 kg/Nm, 308.3 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) |
| Maximum engine speed | 3000 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 | 24 l (25.36 US qt | 21.12 UK qt) |
| Kerb Weight | 3364 kg (7416.35 lbs.) |
| Max. weight | 5897 kg (13000.66 lbs.) |
| Max load | 2533 kg (5584.31 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%) | 7484 kg (16499.4 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) | 221 mm (8.7 in.) |
| Minimum turning circle (turning diameter) | 16.1 m (52.82 ft.) |
| Drivetrain Architecture | Rear wheel drive. Internal Combustion engine. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 6 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, 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 |
INTRODUCTION
The 2011-2014 Chevrolet Silverado 3500 HD II, in its Extended Cab Long Box configuration with the 6.6L Duramax diesel, represented a significant upgrade over its predecessor. Built on the GMT900 platform, this generation benefited from a substantial redesign in 2011, focusing on improved interior refinement, enhanced towing capabilities, and increased diesel engine output. The “II” designation signifies the facelifted version of the GMT900, addressing earlier criticisms regarding interior quality and ride comfort. This particular variant, equipped with the Duramax engine and Allison transmission, was specifically targeted towards customers requiring serious towing and hauling capacity, such as those in the construction, agriculture, and equine industries. The dual rear wheel (DRW) configuration further enhanced stability and payload capacity.
Powertrain & Engine Architecture
At the heart of this Silverado 3500 HD lies the Duramax LML 6.6-liter turbocharged diesel V8 engine. This engine, a cornerstone of Chevrolet’s heavy-duty lineup, produced 397 horsepower at 3000 rpm and a massive 765 lb-ft (1037 Nm) of torque at 1600 rpm. The LML engine featured a cast iron block, aluminum cylinder heads, and a robust crankshaft designed for high-stress applications. Fuel delivery was managed by a high-pressure common rail diesel injection system, optimizing combustion efficiency and reducing emissions. The engine also incorporated a variable geometry turbocharger (VGT) and an intercooler to maximize power output and minimize turbo lag. The Allison 1000 six-speed automatic transmission, renowned for its durability and smooth shifting, was specifically calibrated to handle the engine’s substantial torque. This transmission featured a lock-up torque converter for improved fuel efficiency at highway speeds and a heavy-duty cooling system to prevent overheating during demanding towing conditions.
Driving Characteristics
The Silverado 3500 HD with the Duramax/Allison combination delivered a driving experience markedly different from lighter-duty trucks. While not designed for sporty handling, the truck offered a surprisingly composed ride, especially considering its substantial weight and heavy-duty suspension. The Allison transmission provided smooth and precise gear changes, and the engine’s abundant torque allowed for effortless acceleration, even when heavily loaded. The 6-speed automatic was well-matched to the engine’s powerband, providing ample gearing for both towing and highway cruising. Compared to gasoline-powered Silverado 3500 HD models, the diesel variant offered significantly improved fuel economy when towing and a much higher towing capacity. However, the diesel engine’s increased weight over the front axle could contribute to a slightly nose-heavy feel during cornering.
Equipment & Trim Levels
The Extended Cab Long Box configuration offered a practical balance between passenger space and cargo capacity. Standard features typically included air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. Higher trim levels, such as the LT and LTX, added features like leather upholstery, heated seats, a premium audio system, navigation, and a rear vision camera. Optional extras included a sunroof, upgraded wheels, and various towing packages. The interior design, while functional, prioritized durability over luxury, with robust materials and a straightforward layout. The extended cab provided additional storage space behind the front seats, useful for securing tools or personal belongings.
Chassis & Braking
The Silverado 3500 HD’s chassis was designed for heavy-duty use. It featured a fully boxed frame constructed from high-strength steel, providing exceptional rigidity and durability. The front suspension utilized an independent torsion bar setup with double wishbone control arms, while the rear suspension employed a traditional leaf spring design. The DRW configuration significantly increased stability and payload capacity. 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 braking system was designed to provide ample stopping power, even when towing heavy loads.
Market Reception & Comparison
The 2011-2014 Silverado 3500 HD with the Duramax diesel received generally positive reviews from automotive critics. The engine’s power and torque were widely praised, as was the Allison transmission’s reliability and smoothness. Critics noted the improved interior quality compared to previous generations, although some still found it lacking in refinement compared to offerings from Ford and Ram. Fuel economy, while not exceptional, was considered competitive for a heavy-duty truck. Compared to the 6.0-liter gasoline V8 option, the Duramax diesel offered significantly higher towing capacity and better fuel economy when towing. Compared to the 6.6L Duramax in earlier GMT900 models, the LML version offered increased horsepower and torque, along with improved emissions control.
Legacy
The Duramax LML engine and Allison transmission pairing in the 2011-2014 Silverado 3500 HD has proven to be remarkably durable and reliable. These trucks continue to be highly sought after in the used market, particularly by those requiring a capable and dependable work truck. While maintenance costs for a diesel engine are generally higher than those for a gasoline engine, the Duramax LML has a reputation for longevity, with many examples exceeding 200,000 miles with proper care. The GMT900 platform, while superseded by newer generations, remains a popular choice for those seeking a robust and affordable heavy-duty truck.
