6. a. Any snowmobile, all-terrain vehicle, or dirt bike solely operated for use on a farm shall be exempt from the registration and numbering requirements of P.L.1973, c.307 (C.39:3C-1 et seq.).
b. No registration fee shall be charged for a snowmobile, all-terrain vehicle, or dirt bike owned by the federal government, the State, county or municipal government or subdivision thereof.