[ARC5] Where used?

[jcoward5452 at aol.com]

 Just got a really clean C-39/ARC-5 contract NXsa-38868 s/n 5998 CCT. As this just selects ICS/RADIO, is it a remote control for a crew member other than Pilot?  Or was this for a fixed tuned system with Interphone capability for the Pilot? Has (2) 12 pin connectors marked "K" and one smaller 3 pin with no marking. Has the usual TEL and MIC jacks and the built in cord with the 2 pin jack for a mask mic.VOLUME (variable), and MIC (switch) control for ICS and Radio are the only operator controls.
 And what ICS is compatable? RL-* ?
 Thanks to all,
  Jay