Section 504. Exemptions

The provisions of this article shall not apply to
  any vehicular unit:
    1. Operating over  a  rural  route  and  engaged  exclusively  in  the
  transportation of United States mail under contract.
    2.  Owned  and  operated  by the United States, the state or any other
  state or any county, city, town or municipality in this  state,  or  any
  other state or by any agency or department thereof.
    3.  Owned and operated by a farmer and used exclusively by such farmer
  in transporting his own agricultural commodities and products,  pulpwood
  or  livestock, including the packed, processed, or manufactured products
  thereof, that were originally grown or raised  on  his  farm,  lands  or
  orchard, or when used to transport supplies and equipment to his farm or
  orchard  that are consumed and used thereon or when operated by a farmer
  in transporting farm products from a farm contiguous to his own.
    4. Where the motor vehicle has a gross  weight  of  eighteen  thousand
  pounds  or  less until such time as an election applicable to such motor
  vehicle is filed to  compute  the  tax  under  the  method  provided  in
  subdivision three of section five hundred three of this chapter.
    5.  Used  exclusively  in  the  transportation  of household goods (as
  defined by the commissioner of  transportation  of  this  state  or  the
  interstate  commerce  commission)  by  a  carrier under authority of the
  commissioner of transportation  of  this  state  or  of  the  interstate
  commerce commission.
    6.  Owned  and  operated  by  any  fire  company or fire department as
  defined in section three of the volunteer firemen's benefit law.