[SGRock]

There were a lot of "heads" that joined back in the 80's . The policy then was "Have you ever experimented with illegal controlled substances and if so how many times in the last year?" I knew one guy that said yes and 365 times. he was a Gunny when he related this story to me. If the Corps's policy has not changed, you can admit to drug use ONE TIME. After that you will go up for Court Martial.
I don't think you have a thing to worry about. Like Grimmy said, Be honest and tell the truth. It is in your past.