GMPartsGiant.com offers the wholesale prices for genuine 2015 Cadillac XTS parts. Parts like Turbocharger Cooling System-Rear Unit 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. Model Code: 4 DOOR NOTCHBACK, LUXURY 4 DOOR NOTCHBACK, PLATINUM 4 DOOR NOTCHBACK, PREMIUM 4 DOOR NOTCHBACK.