Just a thought...perhaps you have already been there and done that, but I would think that you could contact the Defense Dept. and get copies of your orders to and from the RVN.
As to other resouces, some your hootch mates should still be out there. With so much time passing, you may want to provide some more info. as to what hootch, your section, or AFSC you had...things get a little "blended" as the years roll on and memories fail.