I flew SYD to Tan Son Nhut via DRW on the QF B707, on Sept 1, 1970 - travelled both ways again about April 1971, and then returned to SYD from Tan Son Nhut via DRW on Aug 12, 1971, as part of my AMF service.
I cannot recall the precise flight times, but I can recall all flights were done largely during daylight hours. I seem to recall a very early departure time from SYD, a stop in Darwin for refuelling and then a direct flight to Tan Son Nhut.
Return trip was similar route and I think we left Tan Son Nhut mid-morning for an arrival around midnight in SYD, after another quick stop in DRW.
I'm sorry I can't be more specific on the timings, I never kept any diary, although I have kept all the correspondence I sent from SVN (which my mother initially kept), and there's a slight chance I may be able to find in that correspondence, some flight timing mentioned.
However, it's only a slight chance, as I've always lived in PER (apart from my time in the AMF) and I had to stay overnight in SYD and catch the QF flight to PER when returning home. The same happened when going to SVN, I had to fly QF to SYD, then catch the QF B707 to SVN.