On February 9, 1968, the Defense Department announced that they were not going to purchase the Lockheed F-12A interceptor, opting instead to remain with the F-106 as the primary interceptor to protect the continental USA from air attack.
On September 3, 1968, Convair issued a proposal for an "improved" interceptor that was to be designated F-106E/F. It was to be compatible with the upcoming airborne warning and control systems as well as with the over the horizon radar defense network. The F-106E/F would have had a longer lose, with a new and improved radar with a look-down/shoot-down tracking and missile launch capability. It would also have had a two-way UHF voice and datalink radio. It would be capable of launching both nuclear and non-nuclear missiles, including the AIM-26 Nuclear Falcon and the AIM-47.
Unfortunately for Convair, this project never got off the drawing board.