NY state has a 'historical' plate. Vehicles have to be 25 years or older.There are restrictions. Looking at the form now they are,"...used for participation in club activities,exhibits,tours,parades,occasional transportation and similar uses ,but is not for general used for daily transportation."
Within the historical registration there is a provision for vintage plates. The plate can be anything, as long as the color is correct for the year of manufacture.For example you could use a 'taxi'' plate on a tractor trailer... The plate(s) cannot be repainted and any registration sticker must display a date that matches the year of manufacture.
My deuce and Stalwart both display vintage NY state 'Official" plates. The GTO has a standard 1970 car plate which NYDMV allowed before 25 years after a meeting with the DMV custom plate dept head (in Albany and because the car has 'historical significance' ).Each carries only a $20/year registration fee. They are all blue w/yellow letters and are often mistaken for Pa plates. The historical registration exempts all vehicles from emission control testing. The official plate has no provision for stickers so they are not required. Unlike regular plates they do not need to be turned if the insurance or registraton lapses.
These old 'Official' plates give both army vehicles an unusual, yet appropriate look. Maybe Pa has a program like NY. JimK