Image taken from the 9th Infantry Regiment, Remembrances Manchu Web Site. Photo could have been taken in 1967. Appears to be taken near some barracks, etc buildings, most likely for A Co, 4th Battalion, 9th Infantry Regiment.
According to the book Vietnam Order of Battle by Shelby L. Stanton, US Army Retired, the 4th Battalion, 9th Infantry [Major Command Unit was 1st Brigade, 25th Infantry Division], arrived in Vietnam 29 April 1966 and Departed 8 Dec 1970. During April 1966 - Feb 1968, may have been located at Cu Chi, RVN; this is the time period Gene Polito was killed.