It was probably 6 Royal Australian Regiment...and the Battle for Long Tan plantation...The Kiwis sent troops to Vietnam as part of Australian deployments, Victor or Whisky Company if I recall.
I am kind of a historian about Australia's deployments to Vietnam. I'm such a geek, I have copies of the real post battle reports from Long Tan from the American National Archives. Shoot, while traveling overseas several years ago, I MET an Australian Vietnam veteran who served in 6 RAR during the war. He was shocked I knew anything about Australia deploying troops to Vietnam.
Don't forget the ANZACS had SAS in Vietnam as well...and not nearly as much firepower on tap as the U.S. forces.
Consider me interested.