NASA's B-57s originally had FY1953 serials (as B-57B/RB-57D), so a few years newer than the M-B Meteors.
They were given FY1963 serials when converted to RB-57F standard (later redesignated WB-57F) for NASA, and the TF33 (JT3D) engines that they now fly with are probably around 10 years newer than the Meteors' Derwents.