[Exchange or sale of bonds; incontestability.]

Such new bonds, when executed, shall be held by the treasurer of the district subject to the orders of the board of directors of the district. Such new bonds may be issued in exchange for the bonds refunded, or may be sold at public or private sale and the proceeds thereof used to acquire for retirement the bonds refunded. Such new bonds shall be incontestable in the hands of bona fide purchasers or holders thereof for value. No proceedings in respect to the issuance of any such bonds shall be necessary except such as are required by this act [73-16-50 to 73-16-53 NMSA 1978].