A Component Comparison from the Previous Year

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Exhaust gas recirculation (EGR) system has been deleted on all applications.
A spacer plate between the crankshaft and flywheel is required for applications using the 4L80-E transmission.
All 2004 applications use a piston with a graphite coated skirt.
The 6.0L RPO LQ9 engine, VIN N, is available as an optional engine package.
RPO HP2 adds a stator, rotor, flexplate, thermal bypass fitting and thermal bypass hose.
The positive crankcase ventilation valve is a non-serviceable fitting on the left rocker arm cover.
The fuel rails for all engines, except the RPO L59, are returnless fuel systems. The fuel pressure regulator for those engines is now a part of the fuel pump module.
First design applications use a piston pin that is floating fit to the piston and press fit to the connecting rod. Second design applications use a piston pin that is full-floating to both the piston and connecting rod.
The first design piston, press-fit pin, and connecting rod are to be serviced as an assembly.