 But the ADC still needed a high-altitude target aircraft, and Martin agreed to modify the remaining EB-57Ds for another 3,000 flight hours, and they served in this role along with other testing roles until the last was retired in July 1979 due to wing-spar fractures

An even larger B-57 reconnaissance version was the wingspan RB-57F.Beginning in 1963, General Dynamics converted 21 B-57 airframes (four of them RB-57Ds) into RB-57Fs.These aircraft performed missions similar to the RB-57D, and the last USAF-operated RB-57F was retired in the early 1970s.