The AIM-4 aka. RB-28 was IR guided (GAR-2 with the IR-seeker from the GAR-4 or aka. The HM-58/AIM-4C ). The RB-27 aka the AIM-26B was semi-active radar guided: GAR-11, which we improved the proximity fuse later on with the introduction of the J35J. We never had a IR guided RB-27. Everything you need to know is in my suggestion I made. (Along with OP’s post)
Hehe, I think you got the wrong one: I actually also said there’s SARH as well as IR Falcons, in response to @Rojasrz34-live’s claim there was no IR Falcon… ;-)
Ohhh yes yes, you’re right about that. As the intended plan was to acquire the AIM-4 Falcon with a SARH seeker. Which the missile had too low explosive yield. Which was the reason why we opted for the AIM-26, aka. RB-27 instead. (Which is also in my post).
But it seems as I confused with something else entirely.