(a) The privilege tax imposed by Act 230, 1927 Regular Session (Local Acts 1927, p. 135), as amended by Act 98, Special Session 1936 (Local Acts 1936, p. 56), on gasoline or motor fuel shall not apply to the storage or sale of gasoline or motor fuel to be used in vehicles, equipment, and aircraft designed primarily for use off of the public roads and highways in Limestone County.
(b) This section shall be retroactive to August 5, 1927, except that Limestone County and the Limestone County Commission shall not be obligated or required to refund any privilege tax heretofore collected pursuant to Act 230, as amended.