Mike? I would like to suggest to you that you zabasearch some people that share his last name in his area and make some phone calls. You could introduce yourself on the phone and tell them that you're looking for the relatives of a "good friend" that you had in the Army back in the 70's and that you've always wondered what happened to him.
Wouldn't you like to know what happened to him or what became of him? I sure would I know that.
I did this very thing that I'm suggesting to you myself back in 2006, you may read it here: http://www.malesurvivor.org/board/ubbthreads.php?ubb=showflat&Number=46805&page=61#Post46805
It's one of my favorite posts. I hope that you would try to do the same.