Could you post a VIN? 2004 is right on the split between 2 diff. injection systems. G2 2004 and up, and Origional HEUI 2004 and back. Quick way to tell is look and see if there is an EGR cooler and a Variable Geometry Turbo (VGT). EGR/VGT is the 2004 & up. Try... Login to read more.