FordPartsGiant.com offers the wholesale prices for genuine 2013 Ford Flex parts. Parts like Rear Doors, Hinges & Weatherstrips 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.