If no agreement is reached within 60 days after the expiration or termination of the agreement or the date on which the agreement became subject to modification under subsection (a) of this section, or if the parties decide upon arbitration but do not agree upon the procedures therefore, an arbitration board
shall be established consisting of 3 members, 1 of whom shall be selected by the Postal Service
, 1 by the bargaining representative of the employees, and the third by the 2 thus selected. If either of the parties fails to select a member, or if the members chosen by the parties fail to agree on the third person within 5 days after their first meeting, the selection shall be made from a list of names provided by the Director. This list shall consist of not less then 9 names of arbitrators of nationwide reputation and professional nature, who are also members of the National Academy of Arbitrators, and whom the Director has determined are available and willing to serve.