um....according to DOD stats, 2,709,965 served "in-country".
I don't have any numbers but there were also quite a few of us who were members of the Tonkin Gulf Yacht Club. (Unless you're only considering in-country troops to be Vietnam veterans, as some people do.)
oops...sorry, that's why the quotes...I should have been clearer...those numbers include the "theater". The RVN Service Medal citation has a good definition of the theater.