(a) The department may issue a permit to a person to operate equipment to move over a state highway one or more portable building units that in combination with the towing vehicle are in excess of the length or width limitations provided by law but less than 80 feet in length.(b) The length limitation in this section does not apply to a truck-tractor or truck-tractor combination towing or carrying the portable building units.(c) In this section, 'portable building unit' means the prefabricated structural and other components incorporated and delivered by the manufacturer as a complete inspected unit with a distinct serial number. The term includes a fully assembled configuration, a partially assembled configuration, or a kit or unassembled configuration, when loaded for transport. Acts 1995, 74th Leg., ch. 165, Sec. 1, eff. Sept. 1, 1995. Amended by Acts 1997, 75th Leg., ch. 165, Sec. 30.146(a), eff. Sept. 1, 1997.