I got my PTSD after NAM. I was on riot duty in Washington DC after the MLK and RFK assassinations. I got shot at there without a chance to reply as we had no ammo.

In Viet Nam I say I was never really in combat. I did my work at a distance. But it wrapped up when I was shot by friendly fire from a dim wit myopic Special Forces from a helicopter. I got shot through the right lung. I dearly wanted to return the favor but could not raise my right arm to do so. My role in the field, I was not really in much danger. I had expensive equipment protecting me. It's not like I was taking hikes through the jungle.

I worked at a rocket factory after. A couple mishaps there really gave me PTSD. I don't want to get graphic. But solid propellant rocket fuel, like C4, cannot be extinguished. So you look on hopelessly while things happen.

My biggest threat in Nam was actually the snakes. I had plenty of run ins with cobras and slinkies.
I may have drank a bit too much in Nam but not addicted then or after. On the quizzes I score zeros for addictions. I never even tries marijuana though I was exposed to plenty of it.