http://www.logsa.army.mil/etms/find_etm.cfm Go to the above site...... enter 8640b in the field marked "TM Title Text" and the available manuals for the 8640B will be listed. I suggest ... https://www.logsa.army.mil/etms/data/A/060577.pdf The last and latest manual for the 8640B non-323 version from 1986. All this courtesy of the US Army... . Mike, W9WIS