Have you ever tried to reconnect with buddies from your past, past tours of duty? Were you successful? How?

I have written many blog postings about my tour of duty in Vietnam and compiled them into a journal that I make available for free on Smashwords. Basically, I have included almost everything I remember of that time and still I get requests for more. A recent request from a young woman whose father, Sgt Levi Carl Warner Jr from corpus Christi Texas, now deceased, who served there during the same time as I ('67 to '68) asking for anything I could tell her to help her write a book about him. She says that he served with Charlie Company, 9th Infantry Division. Obviously, she doesn't know that she's missing some unit identification there. I have responded to her message to let her know that I'm reaching out, here on RP and other social media groups targeting Vietnam Veterans. Even if you don't know this person, there are many who would appreciate suggestions about connecting with buddies from prior tours of duty. I would like to tell her, and others on similar missions, how to research their old units or the units in which loved ones served. How to reconnect with old buddies or rediscover their past, or the past of loved ones. Any suggestions will be gratefully accepted and passed on...