(a) The department may establish criteria to determine whether oil well servicing, oil well clean out, or oil well drilling machinery or equipment is subject to registration under Chapter 502 or eligible for the distinguishing license plate provided by Section 502.146.
(b) Notwithstanding Subsection (a), a vehicle authorized by the department before August 22, 1963, to operate without registration under Chapter 502 may not be required to register under that chapter.
(c) In this section, "oil well servicing, oil well clean out, or oil well drilling machinery or equipment" means a vehicle constructed as a machine used solely for servicing, cleaning out, or drilling an oil well and consisting in general of a mast, an engine for power, a draw works, and a chassis permanently constructed or assembled for one or more of those purposes.