The Department of Defense, specifically the Department of the Navy through NAVSUP Weapon Systems Support, is seeking proposals for the repair and modification of a transponder set, identified by NSN 7R-5826-016863597-RQ, with a quantity of 15 units required. This procurement necessitates engineering source approval due to the flight-critical nature of the item, which mandates that only approved sources may be considered for the contract, as they possess the unique design capabilities and technical data essential for maintaining quality. Interested parties must submit their proposals along with the required source approval documentation within 45 days of this presolicitation notice, and any inquiries should be directed to Chad M. Fichter at (215) 697-2782 or via email at CHAD.FICHTER@NAVY.MIL.