Pub. Util. Code, § 90505

The district may purchase equipment such as cars, trolley buses and motorbuses, and rolling equipment, and may execute agreements, leases and equipment trust certificates in the forms customarily used by private corporations engaged in the transit business appropriate to effect the purchase and leasing of rolling equipment and may dispose of the equipment trust certificates upon the terms and conditions as the board may deem appropriate. All money required to be paid by the district pursuant to the agreements, leases and equipment trust certificates provided for in this section shall be payable solely from the revenues or income to be derived from the transit facilities and from grants and loans as provided in Section 90504. Payment for equipment, or the rental of equipment, may be made in installments and the deferred installments may be evidenced by equipment trust certificates payable solely from revenue or income as provided in this section, and title to the equipment shall not vest in the district until the equipment trust certificates are paid.