The 2007 GMC TopKick largely used a 6.6-liter Duramax turbo-diesel V8 (LBZ) in its heavy-duty configurations, typically paired with an automatic transmission. A gasoline option, the 8.1-liter Vortec V8, was also available on select builds depending on the cab-and-chassis configuration.
This article breaks down the engine options GM offered for the 2007 TopKick, how they varied by model and GVWR, and what buyers should check when evaluating a used TopKick.
Engine options for the 2007 TopKick
Below are the primary engine choices you would encounter on a 2007 TopKick, depending on the cab-and-chassis configuration and GVWR.
- Duramax 6.6-liter turbo-diesel V8 (LBZ): approximately 360 horsepower and 650 lb-ft of torque; commonly paired with an automatic transmission (GM/Allison 1000) in 2007 TopKick heavy-duty configurations.
- Vortec 8.1-liter gasoline V8: approximately 340 horsepower and 450 lb-ft of torque; available on certain gasoline TopKick builds and configurations.
The availability of these engines depended on the specific TopKick model (GVWR) and whether the vehicle was configured for diesel or gasoline operation.
Summary
For the 2007 GMC TopKick, the diesel Duramax 6.6L turbocharged V8 (LBZ) was the most common engine in heavy-duty configurations, delivering strong torque for towing and payload. A gasoline alternative, the 8.1L Vortec V8, was offered on select builds. Always verify the exact engine specification on a used TopKick, as configurations vary by GVWR and body style.