Good old Stationair. Always knows how to get an interesting thread started. Where have you been? Haven't heard from you for a long time.....now back to the thread.
I flew bank runs out of Sydney for Purcells Air Service in three brand new C310R. That was in 1979. Flight Facilities had one on their line as did Hazeltons,so I guess it must be mid 70s although I can't remember seeing any prior to 1979. But then I can't remember where I put the TV remote 5 minutes ago.