After contacting Andrew Crenshaw regarding the ROK White Horse cover he put several other military covers from the Vietnam era online. This cover is one of those, in this case from the ROK 2nd Marine Brigade (later Division), also known as the “Blue Dragon”, stationed in Vietnam from September 1965 onwards.
The sender was a sergeant (병장) “stationed in Vietnam” (=주월) named Kim (=김홍태) who was part of the security section of the military police of the Blue Dragon brigade (=청룡 헌병대 보안과). The letter went to Lee (=이진호), a corporal (상병) at military headquarters of the reserves(?) (사령부 보충대) in unit 7282.