I suggest you go to the Ford website and enter your engine serial number or chassis VIN. Your chassis could be a 1999 or a 2000. Usually RV makers get a shipment of chassis in, store them on the lot until they get an order to build one. Very common for the chassis to be a year older. RV's are registered by the RV maker's date, not the chassis.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI