Ford told some 500 North American fleet customers Monday that it will begin offering an alternative-fuels engine prep package for its 6.8-liter F-450 and F-550 Super Duty chassis cab.

At the annual Ford Fleet Product and Business Conference in Dearborn, Ford presented details of the conversion option, which will become available this fall and enables the use of efficient, clean-burning compressed natural gas (CNG) or propane (LPG, or liquefied petroleum gas).

F-450 and F-550 Super Duty are Ford's latest commercial vehicles to get the alternative-fuel conversion option. Since introducing the option to E-Series and other commercial fleet vehicles last fall, Ford has shipped some 3,000 E-Series vans with CNG/LPG-prepped 5.4-liter and 6.8-liter gas engines to fleet operators such as Verizon and Schwan's Home Delivery Service.

Ford also offers the package on its Transit Connect, including its new Taxi offering with a 2.0-liter four-cylinder gas engine. This fall, Ford also will add CNG/LPG capability to the F-53 motor home chassis and new F-59 commercial strip chassis.

F-450 and F-550's 6.8-liter V-10 engine is well suited to CNG/LPG conversion. The engine comes with hardened exhaust valves and valve seats for improved wear resistance and durability for gaseous fuel systems.

Ford provides calibration guidance to numerous highly competitive CNG and LPG upfitters for E-Series, F-Series and Transit Connect. By following Ford recommendations published in the Body Builders Advisory Service QVM Bulletin Q-185, the converted vehicle maintains its factory engine warranty.