I agree.
Maybe Bell and Kaman got them from the same place way back when... for comparison, can anyone say if the H-3 and H-60 connectors are the same? Lumpy? Kow?
IIRC the H-3 connector was different than the H-60. When I went through HS-1I think I remember that the IPs needed to borrow a helmet when they flew the other aircraft.
As for the Army, when I flew a UH-60A for DLQs, my helmet worked fine in the Army helo.
Best piece of flight gear I had was an ICS cord with a Walkman/iPod jack spliced into it. The AT who did the work wired into my boom mic line, so the whole crew could listen. If I keyed the radio, then the music would transmit over the radio. I would transmit to another helo in PG sometimes. Had to make sure I was on the right freq though. Last thing I needed was to transmit over tower and get busted with it...