North American proposed advanced versions of the Vigilante to the US Air Force an interceptors. One, known as the “Retaliator”, added a liquid-fuel rocket engine to the two J79s, but the Air Force didn’t pursue the concept.
Later, in 1972, in response to an Air Force requirement for an advanced interceptor, North American proposed adding a third J79 in the center bay and arming the “NR-349”, as the new aircraft was designated, with six AIM-54 Phoenix air-to-air missiles. The Air Force didn’t follow up on that concept, either.
Can you say “Colonial Viper”?
UPDATE: Also meant to include this anecdote:
18 RA-5Cs were lost in combat during the war, giving it the highest loss rate of any Navy aircraft in the conflict. 13 Vigilantes were shot down by flak, two were shot down by SAMs, one was shot down by a MiG-21, and the other two were lost to unknown causes over enemy territory.
The loss rate was high because the missions were unusually hazardous. Vigilantes were used for both pre-strike and post-strike reconnaissance. Pre-strike missions were relatively safe, but the North Vietnamese quickly realized after a target was bombed a reconnaissance aircraft would soon arrive to evaluate the damage, and so post-strike missions were generally conducted in the face of an enemy that was thoroughly alert and waiting. Vigilantes flying post-strike reconnaissance missions tried to follow the strike elements in just after the last bombs fell to reduce the risk.
Only 9 of the 36 of the aircrew shot down were rescued, with others either killed or taken prisoner. In one case, the rescue was a grim adventure like something out of an action movie. Lieutenant JG Francis Prendergast was the back-seat RAN on an RA-5C that was shot down over North Vietnam on 9 March 1967. According to one version of the story (there are other versions that differ slightly in details), he was captured near the seashore by North Vietnamese militiamen, with two of them assigned to guard him. One was armed with a rifle, the other with Prendergast’s own 0.38-caliber revolver, standard equipment for aircrew and carried externally in a shoulder holster.
Prendergast carried the revolver with the first two chambers unloaded as a safety measure, and as a backup also had a small 0.22 caliber automatic pistol hidden inside his flight suit. When a rescue helicopter and support aircraft showed up, strafing drove off all the North Vietnamese except the guards, who felt safer staying with Prendergast than running for cover.
This proved a fatal mistake. While the two North Vietnamese were distracted by the noise and confusion, Prendergast pulled out the little automatic, cocked it, and shot the militiaman with the rifle in the head. The other militiaman tried to shoot Prendergast with the revolver, only to find that the hammer fell on an empty cylinder, and was shot himself an instant later. Prendergast swam out to the rescue helicopter and was retrieved.