Any threat, expressed or implied, made directly or indirectly to any person engaged in the business of selling motor vehicles at retail in this state by any person engaged, either directly or indirectly in the manufacture or wholesale distribution only of motor vehicles, that the person will discontinue or cease to sell, or refuse to enter into a contract to sell, or will terminate a contract to sell motor vehicles, whether patented or unpatented, to a person who is engaged in the business of selling motor vehicles at retail, unless that person finances the purchase or sale of any one or a number of motor vehicles only with or through a designated person or class of persons, or sells and assigns the conditional sales contracts, chattel mortgages or leases arising from his retail sales of motor vehicles, or any one or a number of motor vehicles only to a designated person or class of persons, shall be prima facie evidence of the fact that a person engaged in the manufacture or wholesale distribution only of motor vehicles has sold or intends to sell the same on the condition or with the agreement or understanding prohibited in section 49-2401, Idaho Code.