This is a procurement for 67 mechanical transmission assemblies (NSN 1680-00-621-0766) for the KC-135 aircraft, with required deliveries scheduled between March 2028 and February 2029 to Tinker AFB, Oklahoma. The government intends to solicit and negotiate with only one or a limited number of sources, indicating this is not a full and open competition. Qualified sources are listed, and there are specific qualification and IUID marking requirements. The solicitation will be available for download only at SAM.gov, and an ombudsman is appointed to address concerns during the proposal phase.