The 2001-2004 Chevrolet 403 was dubbed the LB7, and was manufactured to go into Silverado HD and Sierra HD trucks.
The LB7 is renowned for its overall reliability and simplicity, especially when compared to newer diesel motors. It featured a first-in-class common rail direct fuel injection, which frequently caused injector failures.
This fault in the engine led Chevrolet/GM to eventually issue a recall on the motors.
Built prior to increasingly stringent emissions standards for diesel engines, the LB7 remains a very popular motor. It is still the foundation for Chevy/GM’s line of Duramx Diesel engines available in new production heavy-duty trucks.
Models manufactured from 2001-2003 were able to hit roughly 235 horsepower. The 2004 models topped out at 300 horsepower.
The 403 was used in 2001-2004 Chevy/GM heavy-duty trucks, including the Chevrolet Silverado and the GMC Sierra.
2004 models were capable of producing more horsepower and more torque.