I was able to recognize the following avionics pieces:
AN/ARC-51 UHF COM
Collins 618F-1A VHF COM
What bothers me is the presence of the ID-250 RMI with two needles in the center of the instrument panel and the ID-249 Course indicator on the right side of the instrument panel. I do not have the proper YO-3A flight manual to consult with, and I am not sure if these indicators were used with the AN/ARN-21 TACAN or the AN/ARN-14 VOR navigation systems on this bird, or with the ADF. The control panel for the nav is unfortunately not visible, so it remains a puzzle whether TACAN, VOR or ADF were originally used in the early YO-3A. Can our experts please help verify what types of TACAN, VOR and ADF were used in the early setup?