GMPartsGiant.com offers the wholesale prices for genuine 2003 Chevrolet Trailblazer 4WD parts. Parts like Wiring Harness/Body are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 6 Cyl 4.2L, 8 Cyl 5.3L. Model Code: 4 DOOR.