As used in this article, the term:

(1) "Dealer" means any person who is engaged in the business of selling heavy-duty equipment motor vehicles at retail and who holds a valid current dealer's resale tax exemption number.

(2) "Heavy-duty equipment motor vehicle" means a motor vehicle with all its attachments and parts which is self-propelled, weighs 5,000 pounds or more, and is primarily designed and used for construction, industrial, maritime, or mining uses, provided that such motor vehicles are not required to be registered and have a license plate.