Sec. 9. (a) When a claim arises from the operation of a motor vehicle leased under a written lease agreement, if under the agreement the lessee agrees to provide coverage for damage resulting from his operation of the vehicle, then the motor vehicle insurance coverage of the lessee is primary. No claim may be made against any coverage available for the vehicle by the lessor until the limits of the motor vehicle insurance coverage provided by the lessee for the vehicle are exhausted.
(b) When a claim arises from the operation of a motor vehicle that is used in the business of transporting property for hire and leased under a written lease agreement, if under the agreement the lessor and lessee agree as to which coverage of the parties' motor vehicle insurance is primary coverage, then the policy of insurance providing that coverage is primary and no claim may be made against any other coverage for the vehicle until the limits of that policy are exhausted.