South Vietnam
Further to the occasional posts on the 'South Vietnam' clasp to the 1962 GSM awarded only to members of the Australian Army Training Team, I have a suspicion that the recipients were later offered the opportunity to 'convert' this to the Vietnam Medal (VM - awarded for operational service in South Vietnam between 1964 and 1973).
Nobody has yet mentioned - in this thread - the Vietnam Logistic and Support Medal (VLSM) that was instituted as late as 1993 but, using the same medal as the VM yet with a plain supporter and different ribbon that included brown to represent the earth and waters of the Mekong River. (Look it up, it really is quite colourful!)
The same medal was used as this design as this had been struck whilst Australia adhered to the Imperial (British) Honours System, which is why it bears the image of HM The Queen. To qualify, one had to be either in the Australian Armed Forces or integrated with them. Thus of the 10,000 or so that were awarded, most of the recipients were the crews of the C130 Hercules and sailors of HMAS Sydney that conveyed the army's heavy vehicles up the Mekong, i.e. temporary visitors. Qantas crews who deployed troops via Richmond, Townsville and Saigon also qualified, as did some medical personnel and - quite recently - qualification was extended to include Sabre pilots and Australian ground forces who had been based at Ubon in Thailand defending the USAF F4s and Jolly Green Giants based there. (RAAF elements based at Vung Tau, etc. qualified for the VM, not the VLSM.)