411A,
Obviously Pilot's have advanced with time and I have been left behind
Next opportunity; i'll read up on if "priority switching" is installed (but not used) on the radio's that i'm using.
I think that the TriStar had the the right idea, further, that a TSO'd avionics installation (or even RNAV only installation) should have a priority switching circuit - especially important if you have only one NAV display.
Thanks for the informative reply.