who claimed to be CO's?
There wasn't much need to assign a CO to Vietnam as the draft produced a glut of soldiers that were never assigned to that conflict.
1,839,994 were inducted via the draft 1964-1973. Approximately 648,000 (32%) of those drafted in those years served in Vietnam.
https://www.sss.gov/About/History-And-Records/Induction-Statistics
http://history-world.org/vietnam_war_statistics.htm