This bit from A/RA-5 Vigilante In Action (Squadron/Signal, Terry Love, 1995): Retaliator was proposed as an F-106 replacement for ADC. Twin J79-GE-10 engines, and a Rocketdyne XLR46-NA-2 for high altitude performance. There was initial USAF interest, but the project wasn't proceeded with. Around 1972 a second project was proposed. This one fitted a third J79-GE-10 in the former weapons tunnel. Projected capabilities were speeds in excess of Mach 2.5 and altitudes over 80,000 feet. Armament was six AIM-54s carried semi-submerged under the fuselage. No apparent interest in this one.
These additions from Wings Of Fame Volume 19: Retaliator was proposed in 1960. The rocket engine was in the former weapons bay. Retaliator was revived in 1970 as NR349 and redesigned as a bid for the IMI (Improved Manned Interceptor, the F-101, F-102, and F-106 replacement). Bifuricated intakes on the upper surface fed the third engine. There's a cutaway of NR349 and a bit of artwork showing two of them flying underneath what would appear to be an eight-engined E-3.
That's all I found so far around here.