(a) The tax imposed by this chapter shall not apply to special fuel sold and delivered to and used by the following persons:
(1) The United States or any governmental agencies thereof;
(2) The State and every political subdivision thereof;
(3) Volunteer fire companies in any of their official vehicles and veterans' or civic organizations in their ambulances when such ambulances are provided on a voluntary basis.
(b) The Department may, for purposes of identification, require that the above persons apply to the Department for a special fuel tax exemption marker to be affixed to the applicable bulk supply talk or pump thereof. The tax exemption marker may be revoked by the Department for just cause.