I was a USAF FAC assigned to the 21st TASS from Nov 1966 - Nov 1967.  I spent the year supporting the 1st Bde of the 101st AB throughout II Corps and southern I Corps.  Our call sign in II Corps was BORON.  In I Corps we were assigned to Americal and our call sign was HELIX.  I flew the O-1E.  Unless I missed it, you do not list BORON as a callsign.  Also, HELIX is listed only for the O-2, you should add the O-1.

Thanks,  Jan Stevens, Lt Col USAF, Ret.