The government is conducting market research via a Sources Sought/RFI for remanufacture of KC-135 Auxiliary Power Units (NSN 2835-01-685-5852, P/N 4550063), considered a supply effort, with performance/destination at Hill Air Force Base. This is not a solicitation, and award may be restricted to qualified sources; interested vendors not previously approved must submit a Source Approval Request package, and foreign participation is restricted. The effort may be competitive and/or a total Small Business Set-Aside under NAICS 336413 (1250 employees), with a potential Firm-Fixed-Price contract. Respondents are asked to demonstrate capabilities in aircraft/flight equipment design, manufacturing/overhaul, APU functional testing, data package possession, and military airworthiness, and to address supply-chain mitigation, Government-Furnished Property custody, First Article Test recommendations, and pricing methods for over-and-above teardown repairs. The notice is for market research only and does not constitute a solicitation, but responsible sources may submit capability statements, proposals, or quotations for consideration.