[Help Proving "boots On Ground In Vietnam"]

I am trying to help my father with his disability claim for Parkinsons. Dad was in the Air Force at Naha, Okinawa from 1960 - 1963 and was flying security clearance missions to vietnam in C130's with the 21st troop carrier squadron - he was a flight engineer. What I've discovered so far is that the Air Force kept no records (unbelievable!) and the only way to prove you were in vietnam is tdy orders with your name on them or a buddy statement from a fellow veteran who can vouch that you were there. Dad's papers were lost in a fire 30 years ago and so far I've been unable to find anyone that knew him. I have a few names of fellows that dad remembers but havent been able to find them. I'm new to this board and didnt know if this is the right place to post dad's information to see if anyone might remember him or have a copy of orders with his name included on them. Thanks in advance for any advice. Sharon