Good sources for finding the names of those who served in the Vietnam War are Veterans History Project and the National Personnel Records Center. These sites can be used to search for information on American survivors and deceased of any war since World War I.
Veterans History Project contains a list of American soldiers who have been contacted or interviewed since World War I.
The National Personnel Records Center in St. Louis, Missouri has information on any military personnel who was discharged or who died in war since World War I. This is a physical center you can visit, but you must follow strict booking rules before any visit.