 The F @-@ 4N ( updated F @-@ 4Bs ) with smokeless engines and F @-@ 4J aerodynamic improvements started in 1972 under a U.S. Navy @-@ initiated refurbishment program called " Project Bee Line " with 228 converted by 1978 . The F @-@ 4S model resulted from the refurbishment of 265 F @-@ 4Js with J79 @-@ GE @-@ 17 smokeless engines of 17 @,@ 900 lbf ( 79 @.@ 379 kN ) , AWG @-@ 10B radar with digitized circuitry for improved performance and reliability , Honeywell AN / AVG @-@ 8 Visual Target Acquisition Set or <unk> ( world 's first operational Helmet Sighting System ) , classified avionics improvements , airframe reinforcement and leading edge slats for enhanced maneuvering . The USMC also operated the RF @-@ 4B with reconnaissance cameras with 46 built . 
