FordPartsGiant.com offers the wholesale prices for genuine 2011 Mercury Grand Marquis parts. Parts like Rear Panels and Rear Package Tray are shipped directly from authorized Ford dealers and backed by the manufacturer's warranty. Parts fit for the following vehicle options. Engine: 8 Cyl 4.6L Romeo SOHC EFI. Transmission: 4-Speed Automatic Transmission 4R75E Livonia.