Jack Cook wrote:
Those would be Mk. 43 freefall nuclear devices. The B-58 was actually cleared to fly with the pylons and weapons on them, but they were never used beyond testing. The proposed use of the B-58 as a low-level supersonic bomber during Vietnam would have seen a quartet of Mk.83 2,000# bombs attached to those hardpoints with a fuel tank or combination fuel tank/bomb rack on the centerline.
From
The Hustler HangarQuote:
The B-58 carried a hefty array of nuclear weapons. After the introduction of the B-58, the Air Force began to have doubts about the utility of a bomber that could only carry a single nuclear weapon, and so between 1961 and 1963 all B-58s were retrofitted with four stub pylons, arranged in tandem under the wing roots, to carry Mk 43 or Mk 61 nuclear weapons. With the centerline weapon the B-58 would now carry five nuclear weapons. The 43rd and the 305th Bomb Wings each had 20 fully armed aircraft/crews standing full time alert, with the capability of launching immediately. Somebody knew we had that capability.