Have authority to purchase or lease or to finance the purchase of highway construction and maintenance equipment under contracts providing for payment in installments over a period of time of not more than 10 years with interest on the unpaid balance owing not to exceed 9%. The purchases or contracts are subject to the bid provisions of Section 6-201.7 of this Code. In single township road districts, sale of road district property including, but not limited to, machinery and equipment shall be subject to elector approval as provided in § 30-50 of the Township Code. A trade in of old machinery or equipment on new or different machinery or equipment shall not be construed as the sale of road district property.