Mont. Code Ann. § 76-15-1005

For contracts for the purchase of vehicles, machinery, equipment, materials, or supplies or for construction, repair, restoration, or maintenance under this chapter in excess of the limit provided in 7-5-2301, supervisors shall comply with the provisions of 76-15-1006 and award a contract according to the selection criteria for proposals and bidding as described in 18-4-303 and 18-4-304.