
David,
Vietnam-era Veterans whose service involved duty on or near the perimeters of military bases in Thailand anytime between February 28, 1961 and May 7, 1975 may have been exposed to herbicides and may qualify for VA benefits.
Source: http://www.publichealth.va.gov/exposures/agentorange/thailand.asp
This document claims possible perimeter AO exposure at Takhli RTAFB all the way up until 1975 which covers the year you were there (1973).
I hope this helps your case. Don't give up.
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