GMPartsGiant.com offers the wholesale prices for genuine 2005 Chevrolet Trailblazer EXT 4WD parts. Parts like Automatic Transmission Oil Cooler Pipes 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 EXT.