FordPartsGiant.com offers the wholesale prices for genuine 2015 Ford Flex parts. Parts like Exhaust Manifold are shipped directly from authorized Ford dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 6 Cyl 3.5L Cyclone Petrol TIVCT, 6 Cyl 3.5L DOHC T/C. Transmission: 6-Speed Automatic Transmission 6F50, 6-Speed Automatic Transmission 6F55.