P.S.
reading what I wrote above makes it sound like I am denying that heroin was a problem in Vietnam.....I could have written it clear, to make the point that it came LATER than 1968, at least in anything one could possibly interpret as widespread......and I’m still not sure it was as widespread later as it was made to seem.
Can't speak for other units, but the stories I heard from friends at the time suggest it was pretty widespread.