Mmmmm ...
The last S58T that I saw in Australia was on Thursday Island (refuelling) and then departing towards PNG .... I think sometime around September of 1979.
It was in Airfast (Indonesia) colours and was being ferried by one John Bayfuss (?) to someplace in Indonesia..... but I cannot for the life of me remember why?
I think also that Helitrans (Australia) in Cairns operated 58Ts for sometime but again cannot remember the details though I remember seeing them there at the airport (so many years ago).
I was also told of a Super Frelon which was in Australia (for operations in PNG) in the very early 70's but had some problems again with the then DCA re helipad requirements.
I do know that my (Oz) Senior Commercial Helicopter exams had in them quite a few questions based on S58t operations and that was in 1982! so I assume they (the 58Ts) were on the Australian register at some time.
Cheers