NOTE! "Wikipedia" omission: ONLY the 105mm howitzer battalions, such as the 2/9th Arty, were tasked to provide Forward Observers. Consequently, just a "privileged few" served with the "grunts" as a full-time assignment. Many claim to be "Forward Observers" who merely went on a mission or two, but were actually assigned to base units, not exposed to combat in the field on a daily basis.
"Let's clarify our terms...it's very important. A "real" FO is one who is assigned to be the Infantry Company commander's school-trained artillery expert...not some yahoo who overheard conversations on calling for indirect fire. That FO walks the same ground as his company grunts do, humping the jungle, and spend 24 hours out there, as long as ordered. The FO in the field can expect to participate in...and perhaps become a KIA from...a firefight, a mortar attack, a booby-trap or friendly fire...at any time. He'd better be right and better know what he is doing. It's not a "thrill-seeking" job, it is a heavy responsibility."