Im almost 100% positive though that ive heard QF 73's on MC broadcasting their intentions because i thought it was very strange hearing a large a/c giving CTAF like calls when i only ever hear them using their flight numbers in CTA.
Another point is my old man and best mate do alot of drilling there, one being on a barge behind barrow right now, and when the last cyclone came through they evacuated the entire island with "large Qantas jets with engines on the wings" as my mate put it. I tried to probe him further deciphering between a 146 and a 73, however he said the seating was 3 and 3......sounds like a 73 to me!