The Chevrolet Silverado 3500 HD II, specifically the Extended Cab Long Box configuration with the 6.6-liter Duramax Turbo Diesel V8 engine producing 397 horsepower and paired with a 6-speed Allison automatic transmission and four-wheel drive, represents a significant iteration of Chevrolet’s heavy-duty pickup 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 efficiency aimed at the demanding needs of American truck buyers. This particular trim level occupied a sweet spot in the Silverado 3500 HD lineup, offering substantial towing and payload capacity without the premium price tag of the fully-loaded models.
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) 4WD SRW 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 | 8.3 kg/Hp, 119.8 Hp/tonne |
| Weight-to-torque ratio | 3.2 kg/Nm, 313 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 | 3313 kg (7303.91 lbs.) |
| Max. weight | 5262 kg (11600.72 lbs.) |
| Max load | 1949 kg (4296.81 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) | 213 mm (8.39 in.) |
| Minimum turning circle (turning diameter) | 15.8 m (51.84 ft.) |
| 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 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 |
Powertrain & Engine Architecture
The heart of this Silverado 3500 HD II is the Duramax LML 6.6-liter turbocharged diesel V8. This engine represents a significant evolution of the Duramax design, incorporating a redesigned combustion chamber, improved fuel injection system, and a more robust cooling system. The LML utilizes a common-rail direct injection system, delivering fuel at extremely high pressures for optimized combustion efficiency and reduced emissions. The engine also features a variable geometry turbocharger (VGT) which adjusts airflow to optimize performance across the engine’s operating range. The overhead valve (OHV) valvetrain, while traditional, is known for its durability and simplicity. The 6-speed Allison automatic transmission, a hallmark of heavy-duty GM trucks, is specifically tuned to handle the immense torque output of the Duramax engine. It features a lock-up torque converter for improved fuel economy at highway speeds and provides smooth, confident shifting even under heavy loads.
Driving Characteristics
The 397 horsepower and 765 lb-ft of torque delivered by the Duramax engine and Allison transmission combination provide substantial pulling power and a confident driving experience. While not as quick off the line as gasoline-powered trucks, the Silverado 3500 HD excels in situations requiring low-end grunt. The automatic transmission’s gear ratios are optimized for towing, keeping the engine within its peak torque band when hauling heavy loads. Compared to the 6.0L gasoline V8 option, the Duramax offered significantly more torque and better fuel economy, especially when towing. Compared to higher-output Duramax variants (like those found in later model years), this 397 hp version offered a balance between power and affordability. The manual transmission options, while offering more driver control, were less popular for those prioritizing ease of use and comfort during long hauls.
Equipment & Trim Levels
The Silverado 3500 HD II in this configuration typically came standard with features like air conditioning, power windows and locks, a basic audio system, and vinyl upholstery. The Extended Cab provided additional rear seating, though legroom was limited. Optional extras included leather upholstery, a premium audio system, navigation, heated seats, and various towing packages. The LT trim level, often paired with this engine and transmission, added features like chrome exterior trim, upgraded interior materials, and additional convenience features. The overall interior design was functional and durable, prioritizing practicality over luxury.
Chassis & Braking
The Silverado 3500 HD II utilizes a robust body-on-frame construction, providing a solid foundation for heavy-duty work. The front suspension features an independent torsion bar setup with double wishbones, while the rear utilizes a traditional leaf spring rigid axle configuration. This setup prioritizes load-carrying capacity and durability. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power even when towing. An Anti-lock Braking System (ABS) is standard. The rear axle ratio varied depending on the specific configuration, influencing both towing capacity and fuel economy.
Market Reception & Comparison
The 2011-2014 Silverado 3500 HD with the 6.6L Duramax and Allison automatic was generally well-received by critics and consumers alike. It was praised for its powerful engine, smooth transmission, and impressive towing capabilities. Fuel economy, while not exceptional, was competitive for a heavy-duty diesel truck. Compared to Ford’s Super Duty and Ram’s heavy-duty offerings, the Silverado 3500 HD was often seen as a balanced option, offering a good combination of performance, comfort, and value. Some critics noted the interior design was less refined than some competitors, but the Silverado’s overall reliability and durability were highly regarded.
Legacy
The Duramax LML engine and Allison transmission pairing have proven to be exceptionally durable and reliable. Well-maintained examples of this Silverado 3500 HD II continue to command respectable prices in the used car market. The engine is known for its longevity, often exceeding 200,000 miles with proper maintenance. Common maintenance items include regular oil changes, fuel filter replacements, and coolant flushes. The availability of aftermarket performance upgrades allows owners to further enhance the engine’s power and efficiency. This generation of Silverado 3500 HD remains a popular choice for those seeking a capable and dependable heavy-duty truck.
