The EA-6B was developed beginning in 1966 as a replacement for EKA-3B Skywarriors for the U.S. Navy. The forward fuselage was lengthened to create a rear area for a larger four-seat cockpit, and an antenna fairing was added to the tip of its vertical stabilizer. Grumman was awarded a $12.7 million contract to develop an EA-6B prototype on 14 November 1966. The Prowler first flew on 25 May 1968, and it entered service on aircraft carriers in July 1971. Three prototype EA-6Bs were converted from A-6As, and five EA-6Bs were developmental airplanes. A total of 170 EA-6B production aircraft were manufactured from 1966 through 1991.