The GMC Sierra 1500 III, specifically the Extended Cab Long Box configuration with the 6.0-liter Vortec V8 engine and automatic transmission, was a full-size pickup truck produced from 2007 to 2010. This generation, known as the GMT900, represented a significant redesign for GMC’s light-duty trucks, focusing on improved refinement, capability, and styling compared to its predecessor. The Extended Cab offered a balance between passenger space and bed length, making it a popular choice for both work and family use. This particular variant, equipped with the 6.0L V8 and automatic transmission, occupied a mid-to-upper position in the Sierra 1500 lineup, offering a substantial increase in power and towing capacity over the base engine options.
Technical Specifications
| Brand | GMC |
| Model | Sierra 1500 |
| Generation | Sierra 1500 III (GMT900) Extended Cab Long Box |
| Type (Engine) | 6.0 Vortec V8 (367 Hp) Automatic |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 6 |
| Doors | 2 |
| Fuel consumption (urban) | 18.1 l/100 km (13 US mpg, 15.6 UK mpg, 5.5 km/l) |
| Fuel consumption (extra urban) | 13.1 l/100 km (18 US mpg, 21.6 UK mpg, 7.6 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Power | 367 Hp @ 5600 rpm |
| Power per litre | 61.5 Hp/l |
| Torque | 508 Nm @ 4300 rpm (374.68 lb.-ft. @ 4300 rpm) |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L76 |
| 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 | 91.95 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 |
| Engine oil capacity | 5.7 l (6.02 US qt, 5.02 UK qt) |
| Coolant capacity | 13.6 l (14.37 US qt, 11.97 UK qt) |
| Max. weight | 3130 kg (6900.47 lbs.) |
| Trunk (boot) space – maximum | 2138 l (75.5 cu. ft.) |
| Fuel tank capacity | 128 l (33.81 US gal, 28.16 UK gal) |
| Length | 6325 mm (249.02 in.) |
| Width including mirrors | 2029 mm (79.88 in.) |
| Height | 1870 mm (73.62 in.) |
| Wheelbase | 4001 mm (157.52 in.) |
| Front track | 1730 mm (68.11 in.) |
| Rear (Back) track | 1702 mm (67.01 in.) |
| Ride height (ground clearance) | 230 mm (9.06 in.) |
| Minimum turning circle (turning diameter) | 15.6 m (51.18 ft.) |
| Approach angle | 16.2° |
| Departure angle | 22.8° |
| Ramp-over (brakeover) angle | 18° |
| Drivetrain Architecture | Rear wheel drive |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission Hydra-Matic |
| Front suspension | Independent coil spring |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs |
| Rear brakes | Drum |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric Steering |
| Tires size | 245/70 R17 |
| Wheel rims size | 7.5J x 17 |
Powertrain & Engine Architecture
The heart of this Sierra 1500 variant is the 6.0-liter Vortec L76 V8 engine. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. The L76 features a cast iron block with aluminum cylinder heads, a 9.6:1 compression ratio, and a two-valve-per-cylinder (OHV) configuration. Fuel delivery is handled by a multi-port fuel injection system, providing precise fuel metering for optimal performance and efficiency. The engine produces 367 horsepower at 5600 rpm and 508 Nm (374.68 lb-ft) of torque at 4300 rpm. The Hydra-Matic 6-speed automatic transmission was the standard pairing for this engine. This transmission offered smooth shifting and helped to maximize the engine’s powerband, providing adequate acceleration and towing capability. The transmission was electronically controlled, adapting shift points based on driving conditions and throttle input.
Driving Characteristics
The 6.0L V8 and 6-speed automatic combination delivered a noticeable step up in performance compared to the base 4.8L or 5.3L engine options. While not as quick as some of the sportier pickup trucks on the market, the Sierra 1500 with this powertrain offered ample power for everyday driving, hauling, and towing. The automatic transmission provided smooth and predictable shifts, making it easy to drive in a variety of conditions. The gear ratios were optimized for both acceleration and fuel economy, although fuel consumption remained relatively high by modern standards. Compared to a manual transmission equipped Sierra, the automatic offered convenience but sacrificed some driver control and potentially a slight amount of fuel efficiency.
Equipment & Trim Levels
The Extended Cab Long Box 6.0L variant typically came standard with features such as air conditioning, power windows and locks, a CD player, and cloth upholstery. Higher trim levels, like the SLT, added features such as leather upholstery, heated seats, a premium sound system, and chrome exterior accents. Optional extras included a navigation system, sunroof, and upgraded towing packages. The interior design was functional and durable, prioritizing practicality over luxury. The extended cab provided additional seating for passengers, although the rear seats were best suited for shorter trips.
Chassis & Braking
The GMT900 Sierra 1500 utilized a body-on-frame construction, providing a robust and durable platform. The front suspension featured independent coil springs, while the rear suspension employed a traditional leaf spring setup. This configuration offered a comfortable ride quality, even when carrying heavy loads. Braking duties were handled by ventilated discs at the front and drum brakes at the rear. An Anti-lock Braking System (ABS) was standard, enhancing safety and control during emergency braking situations. The steering system was a rack-and-pinion setup with power assist, providing responsive and precise steering feel.
Market Reception & Comparison
The 6.0L V8-equipped Sierra 1500 was generally well-received by critics and consumers alike. It was praised for its strong performance, comfortable ride, and spacious interior. However, fuel economy was a common criticism, as the large V8 engine consumed a significant amount of gasoline. Compared to the 5.3L V8, the 6.0L offered a substantial increase in power and towing capacity, but at a higher price point. The 6.0L was often seen as a good choice for buyers who frequently towed heavy trailers or needed extra power for work-related tasks. Reliability was generally good, although some owners reported issues with the electronic throttle control system.
Legacy
The GMT900 Sierra 1500, and particularly the 6.0L V8 variant, remains a popular choice in the used truck market today. The Vortec 6.0L engine is known for its durability and relatively simple maintenance requirements. While fuel economy is not its strong suit, the truck’s robust construction and ample power make it a capable and reliable workhorse. Parts availability is generally good, and the truck’s relatively straightforward design makes it relatively easy to repair. These trucks are often sought after by those needing a dependable pickup for hauling, towing, or general-purpose use, and continue to represent a solid value in the used truck market.
