Drug and aclcohol testing became standard while i was in the navy and as I recall it was circa 82 that it began
Put Hardball on.
The only drug testing that was done in the early 70's was those returning from Vietnam and that was spot checked. No routine drug testing was done for flight physicals that I know of and I worked in the office that got stuck with the reports coming out of SEA on drug usage.
That's about what I recall. I joined the Navy in 79, and while no one openly condoned drug use it wasn't uncommon to hear "I don't care what you do on your own time, just don't bring it on duty." That was soon replaced with the random whiz quiz and "Not on MY watch, not on MY ship, not in MY navy."