The GMC Sierra 1500 III, specifically the Regular Cab Long Box configuration with the 5.3 Vortec V8 engine and four-wheel drive, was a mainstay of GMC’s full-size pickup truck lineup from 2007 to 2010. Representing the GMT900 generation, this variant occupied a sweet spot for buyers needing a capable work truck without the added expense of crew cab amenities. It catered to individuals and businesses prioritizing hauling and towing capacity alongside the reliability of the Vortec engine. This model year marked a significant redesign for the Sierra, introducing a more refined interior and updated exterior styling compared to its predecessor.
Technical Specifications
| Brand | GMC |
| Model | Sierra 1500 |
| Generation | Sierra 1500 III (GMT900) Regular Cab Long Box |
| Type (Engine) | 5.3 Vortec V8 (315 Hp) 4WD Automatic |
| Start of production | 2007 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 3 |
| 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 (Gasoline) |
| Weight-to-power ratio | 7.2 kg/Hp, 138.7 Hp/tonne |
| Weight-to-torque ratio | 5 kg/Nm, 201.7 Nm/tonne |
| Power | 315 Hp @ 5200 rpm |
| Power per litre | 59.1 Hp/l |
| Torque | 458 Nm @ 4400 rpm (337.8 lb.-ft. @ 4400 rpm) |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | LY5 |
| 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 | 2271 kg (5006.7 lbs.) |
| Max. weight | 3084 kg (6799.06 lbs.) |
| Max load | 813 kg (1792.36 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%) | 4445 kg (9799.55 lbs.) |
| Length | 5702 mm (224.49 in.) |
| Width including mirrors | 2031 mm (79.96 in.) |
| Height | 1875 mm (73.82 in.) |
| Wheelbase | 3378 mm (132.99 in.) |
| Front track | 1730 mm (68.11 in.) |
| Rear (Back) track | 1702 mm (67.01 in.) |
| Ride height (ground clearance) | 241 mm (9.49 in.) |
| Minimum turning circle (turning diameter) | 15.4 m (50.52 ft.) |
| Approach angle | 17° |
| Departure angle | 23.3° |
| Ramp-over (brakeover) angle | 21.8° |
| 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
At the heart of this Sierra 1500 variant lies the 5.3-liter LY5 Vortec V8 engine. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. The LY5 features a cast iron block and aluminum cylinder heads, contributing to its durability. It utilizes a multi-port fuel injection system, delivering fuel directly to each cylinder for efficient combustion. The overhead valve (OHV) valvetrain, while not as technologically advanced as overhead cam designs, proved reliable and cost-effective. The engine produces 315 horsepower at 5200 rpm and 458 lb-ft of torque at 4400 rpm. The Hydra-Matic 6-speed automatic transmission was the sole transmission option for this configuration. This transmission offered smooth shifting and helped optimize fuel economy compared to older 4-speed automatics. The 6L80E transmission is known for its durability and ability to handle the engine’s torque output.
Driving Characteristics
The 5.3L V8 and 6-speed automatic combination provided a balance between power and usability. While not as quick as the available 6.0L V8, the 5.3L offered ample power for daily driving and towing. The automatic transmission’s gear ratios were tuned for both acceleration and fuel efficiency. In real-world conditions, the truck felt capable when hauling moderate loads, and the 4WD system provided confident traction in various weather conditions. Compared to manual transmission versions, the automatic offered a more relaxed driving experience, particularly in city traffic. However, some drivers noted a slight decrease in fuel economy and a less direct connection to the engine.
Equipment & Trim Levels
The Regular Cab Long Box 5.3L 4WD Sierra typically came standard with features like air conditioning, power windows and locks, and a basic audio system. Higher trim levels, such as the SLT, added features like leather upholstery, heated seats, a premium audio system, and chrome exterior accents. Optional extras included a navigation system, sunroof, and upgraded towing packages. The interior, while functional, was generally more utilitarian than the interiors found in crew cab models. The bench seat configuration provided seating for three passengers, but rear legroom was limited.
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 prioritized load-carrying capacity and durability over refined ride quality. Braking duties were handled by disc brakes up front and drum brakes in the rear. An anti-lock braking system (ABS) was standard. The truck’s relatively high ground clearance (9.49 inches) allowed for moderate off-road capability.
Market Reception & Comparison
The 2007-2010 GMC Sierra 1500 with the 5.3L V8 and automatic transmission was well-received by critics and consumers alike. It was praised for its strong engine, comfortable ride, and capable towing capacity. Compared to the 4.8L V8 option, the 5.3L offered a significant performance boost. The 6.0L V8 provided even more power, but at a higher price point. Fuel economy was average for a full-size pickup truck of its era, and reliability was generally good, although some owners reported issues with the active fuel management system (AFM), which deactivated cylinders to improve fuel economy.
Legacy
The LY5 5.3L Vortec V8 has proven to be a remarkably durable engine, and many examples are still on the road today with high mileage. The Hydra-Matic 6-speed automatic transmission is also known for its longevity. In the used car market, these Sierra 1500s represent a good value for buyers seeking a capable and reliable work truck. However, potential buyers should be aware of the potential for AFM issues and should inspect the truck thoroughly for signs of wear and tear. The GMT900 generation Sierra 1500 remains a popular choice for those who need a traditional, body-on-frame pickup truck with proven mechanicals.
