The GMC Sierra 1500 III, specifically the Extended Cab Long Box configuration with the 5.3-liter Vortec V8 engine producing 320 horsepower, was a popular full-size pickup truck sold in North America from 2007 to 2010. Representing the third generation of the Sierra 1500 (GMT900 platform), this variant occupied a sweet spot in the lineup, offering a balance of capability, space, and affordability. It catered to buyers needing a versatile truck for both work and personal use, without the expense of the higher trim levels or the reduced practicality of a regular cab.
Technical Specifications
| Brand | GMC |
| Model | Sierra 1500 |
| Generation | Sierra 1500 III (GMT900) Extended Cab Long Box |
| Type (Engine) | 5.3 Vortec V8 (320 Hp) 4WD Automatic FlexFuel |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 6 |
| Doors | 2 |
| Fuel consumption (urban) | 16.8 l/100 km (14 US mpg, 16.8 UK mpg) |
| Fuel consumption (extra urban) | 12.4 l/100 km (19 US mpg, 22.8 UK mpg) |
| Fuel Type | Petrol / Ethanol – E85 |
| Weight-to-power ratio | 7.8 kg/Hp, 128.2 Hp/tonne |
| Weight-to-torque ratio | 5.4 kg/Nm, 184.7 Nm/tonne |
| Power | 320 Hp @ 5200 rpm |
| Power per litre | 60.1 Hp/l |
| Torque | 461 Nm @ 4200 rpm (340.02 lb.-ft. @ 4200 rpm) |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | LMG |
| Engine displacement | 5328 cm3 (325.13 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 96.01 mm (3.78 in.) |
| Piston Stroke | 91.95 mm (3.62 in.) |
| Compression ratio | 9.9:1 |
| 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 | 14.1 l (14.9 US qt | 12.41 UK qt) |
| Kerb Weight | 2496 kg (5502.74 lbs.) |
| Max. weight | 3175 kg (6999.68 lbs.) |
| Max load | 679 kg (1496.94 lbs.) |
| Trunk (boot) space – maximum | 2138 l (75.5 cu. ft.) |
| Fuel tank capacity | 128 l (33.81 US gal | 28.16 UK gal) |
| Permitted trailer load with brakes (12%) | 4173 kg (9199.89 lbs.) |
| Length | 6325 mm (249.02 in.) |
| Width including mirrors | 2029 mm (79.88 in.) |
| Height | 1868 mm (73.54 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) | 240 mm (9.45 in.) |
| Minimum turning circle (turning diameter) | 15.6 m (51.18 ft.) |
| Approach angle | 16.4° |
| Departure angle | 22° |
| Ramp-over (brakeover) angle | 17.8° |
| 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 Hydra-Matic |
| Front suspension | Independent coil spring |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Disc, 330×30 mm |
| Rear brakes | Drum, 295×60 mm |
| 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 was the 5.3-liter (325 cubic inch) Vortec 5300 V8 engine, designated as the LMG code. This engine was a member of the Vortec family, known for its robust construction and relatively simple design. It featured a cast iron block with aluminum cylinder heads, and utilized a 9.9:1 compression ratio. The engine employed a multi-port fuel injection system, delivering fuel to each cylinder individually for optimized combustion. The overhead valve (OHV) valvetrain, while not as technologically advanced as overhead cam designs, contributed to the engine’s durability and ease of maintenance. The 4L80-E four-speed automatic transmission, a Hydra-Matic design, was the standard transmission for this configuration. This transmission was known for its strength and reliability, well-suited to the demands of towing and hauling. The FlexFuel capability allowed the engine to run on gasoline or a blend of up to 85% ethanol (E85).
Driving Characteristics
The 320 horsepower and 340 lb-ft of torque provided by the 5.3L V8 and 4L80-E transmission combination delivered adequate performance for everyday driving and moderate towing. While not as quick as the 6.0L V8 or the 6.6L Duramax diesel options, the 5.3L offered a good balance of power and fuel economy. The four-speed automatic transmission, while reliable, lacked the refinement and efficiency of newer transmissions with more gears. Gear ratios were optimized for towing and hauling, resulting in a slightly lower final drive ratio compared to models equipped with the smaller 4.8L V8. Acceleration was respectable, but the truck’s weight and the transmission’s gearing meant it wasn’t particularly sporty. The 4WD system provided enhanced traction in inclement weather and off-road conditions.
Equipment & Trim Levels
The Extended Cab Long Box 5.3L 4WD Sierra 1500 typically came standard with features like air conditioning, power windows and locks, a CD player, and cloth upholstery. The Extended Cab configuration offered a small rear seat, suitable for occasional passengers. Optional extras included leather upholstery, a premium sound system, a navigation system, and a power sunroof. Trim levels varied, but generally included base models, SLE, and SLT. The SLE trim added features like alloy wheels, upgraded interior trim, and a remote keyless entry system. The SLT trim offered even more luxury features, such as leather seats, heated front seats, and a Bose sound system.
Chassis & Braking
The GMT900 platform utilized a body-on-frame construction, providing a robust and durable chassis. The front suspension consisted of independent coil springs, while the rear suspension employed a traditional leaf spring setup. This configuration was designed to handle heavy loads and provide a comfortable ride. Brakes were disc brakes in the front (330x30mm) and drum brakes in the rear (295x60mm). An anti-lock braking system (ABS) was standard. The truck’s relatively high ground clearance (9.45 inches) allowed for moderate off-road capability.
Market Reception & Comparison
The 5.3L V8-equipped Sierra 1500 was well-received by consumers and critics alike. It was praised for its reliability, capability, and comfortable ride. Compared to the 4.8L V8, the 5.3L offered a significant power boost, making it a better choice for those who frequently towed or hauled heavy loads. Compared to the more expensive 6.0L V8 and Duramax diesel options, the 5.3L provided a more affordable entry point into the full-size truck market. Fuel economy was average for a full-size pickup truck, but the FlexFuel capability offered some cost savings for those who had access to E85 fuel.
Legacy
The GMT900 Sierra 1500, particularly the 5.3L V8 models, have proven to be remarkably durable vehicles. The LMG engine is known for its longevity, and with proper maintenance, can easily exceed 200,000 miles. The 4L80-E transmission is also highly regarded for its reliability. Today, these trucks are readily available on the used car market at affordable prices. They remain a popular choice for those seeking a capable and dependable work truck or a versatile family vehicle. However, potential buyers should be aware of potential issues such as oil leaks, corrosion, and wear and tear on suspension components. Overall, the GMC Sierra 1500 III 5.3L V8 4WD remains a solid and dependable truck with a lasting legacy.
