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, or any agent of any such person, who is engaged in the business of financing the purchase or sale of motor vehicles or of buying conditional sales contracts, chattel mortgages or leases on motor vehicles in this state, and is affiliated with or controlled by any person engaged, directly or indirectly in the manufacture or wholesale distribution only of motor vehicles, that the person engaged in the manufacture or distribution shall terminate his contract with or cease to sell motor vehicles to a person engaged in the sale of motor vehicles at retail in this state unless that person finances the purchase or sale of any one or any number of 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 sale of motor vehicles, or any one or any number thereof only to a person engaged in financing the purchase or sale of motor vehicles, or in buying conditional sales contracts, chattel mortgages or leases on motor vehicles, shall be presumed to be made at the direction of and with the authority of the person engaged in the manufacture or distribution of motor vehicles, and shall be prima facie evidence of the fact that the person engaged in the manufacture or wholesale distribution only of motor vehicles has sold or intends to sell them on the condition or with the agreement or understanding prohibited in section 49-2401, Idaho Code.