Originally, it was 3 (RND, CBM, SPS).
In 2001, RND and CBM consolidated to VAD.
The 2005 BRAC eliminated VAD, and returned the 49th to CBM, the 435th to RND, and opened up the 434th at DLF and the 3rd at END. That was a BRAC decision, not a USAF decision. There were LOTS of USAF people who opposed moving IFF from VAD, and who opposed opening up the two new squadrons -- but it had to be done, anyway.