When Douglas were assigned the contract for the F6D Missileer, it was decided that an airborne testbed for the weapon system would be useful, so an F3D-2 was modified to carry a pair of Bendix AAM-N-10 Eagle missiles along with a modified radar giving compatibility with the new missile. The additional electronics required for the radar meant that the original gun armament had to be removed to provide space.
By the time the aircraft was ready to fly ( problems with the radar caused nearly 20 months of delay ) the Missileer programme had been terminated, as had the eagle missile. However it was decided to press on with the F3D-4, but carrying the AIM-47 Falcon, as a complement to the Air Force's YF-12 programme. A number of succesful test firings were completed, and serious consideration was given to a Douglas proposal to put the F3D-4 into production as a cut price Missileer, but the same concerns that killed the F6D were raised, and coupled with the fact that the F3D-4 could only carry two of the big Falcons saw the proposal declined.
Matchbox F3D-2, missiles from an Italeri YF-12A. Camera flash give the impression in some of the pics that the colour is a lighter blue than is actually the case - really it is quite dark blue