GMPartsGiant.com offers the wholesale prices for genuine 2020 Cadillac CT6 parts. Parts like Entertainment System 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 4.2L. Model Code: 4 DOOR SEDAN, BASE 4 DOOR SEDAN, PLATINUM 4 DOOR SEDAN, PREMIUM 4 DOOR SEDAN, V-SPORT 4 DOOR SEDAN.