Aviation stuff. The prefixes on the serial numbers, “58” and “59,” refer to the fiscal years of procurement, 1958 and 1959. Actual delivery would have been a year or so later. Now that the Air Force has (again) retired the latest iteration of the historic DC-3, the Basler UC-47T, KC-135s are the oldest aircraft in service, some dating back to 1957. The C-130 and B-52 have both been in service longer, 1956 and 1955 respectively, but current service aircraft are later versions. All remaining B-52s are “H” models, delivered in 1961-62. The oldest still serving C-130s are from the mid to late 70s, with production of modernized versions continuing.