GenX veterans: Does anyone know that you served?

My grandfather served. My dad and I were unable due to back problems, and we would later find out my grandfather was glad we were unable to. I wish I knew what he actually did in the military, but I got so many conflicting stories. I know he served, because I saw the papers and he had old memorabilia and he retired as a Gunnery Sergeant. The conflicting stories are about what he actually did and WHEN he was actually deployed. He met my grandmother while he was on leave and they got married the next week before he had to go back and my aunt is in her 70's, which would make it in the 40's at the latest, which I took as World War II. However, talking to my grandmother later, she said he was in the Korean War, which wouldn't have tracked with his supposed Retirement from his civilian job at 50 years in maybe the late 90's, POSSIBLY early 2000's. When he transitioned to civilian, he went into automotive at a car dealership as a mechanic and the story behind it was that that was what he did in the military. I mentioned it to him later, and he changed the story to in his downtime he would go over to motor pool and learn from them. That was brought up when my grandparents were just fed up with how long I had let my hair grow and he offered to cut it himself since he was a barber. But there was also an instance where he said he was in the armory. I don't know, he and my grandmother both passed before I could really sit down and get it out of them. I know he saw action though, because when my sons were born, they would get in the floor and crawl around like soldiers when they reached a certain age. He had a PTSD moment over it, started yelling at them and me to "Get them! Get them!" which scared everyone involved. He apparently had the presence of mind that he KNEW it was PTSD, but it triggered him because "The enemy would use children as tunnel rats and he had encounters with them" according to my grandmother when all was settled down. The look of shame on his face afterwards was heartbreaking as well. Sitting down and going over all this with my wife after they both passed and wanting to get to the truth of it, me and my wife just joke and say he was some kind of black ops since there were so many different things he would admit to. I don't think I'll ever know. All that to say, I know that there are those out there that the "Thank you for your service" phrase can be troubling to them. I've had co-workers actually make the comment of "Don't thank me for what I did in the service, there's nothing to be thankful for" and you can just tell there's stuff that haunts them. My granddad was so serious about Memorial Day, but couldn't have cared less about Veteran's Day. I've found the ones that REALLY served the country don't even want to be acknowledged for it. And that's kind of sad especially taking into account the mental health crisis for when they get back home and are just dumped back into the civilian population.