GMPartsGiant.com offers the wholesale prices for genuine 2009 Cadillac STS parts. Parts like Roof Headliner are shipped directly from authorized GM dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 6 Cyl 3.6L, 8 Cyl 4.4L, 8 Cyl 4.6L. Model Code: 4 DOOR, 4 DOOR(RHD), V 4 DOOR.