A U.S. Marine Corps North American OV-10A <i>Bronco</i> from Marine Observation Squadron VMO-1 in flight over Vietnam, in 1970. Note the GPU-2 20 mm gun pod on the centerline station.
USMC
Official U.S. Marine Corps photograph in: <i>U.S. Marines in Vietnam. Vietnamization and Redeployment 1970-1971</i> <a rel="nofollow" class="external text" href="http://www.marines.mil/Portals/59/Publications/U.S.%20Marines%20In%20Vietnam%20Vietmanization%20and%20Redeployment%201970-1971%20PCN%2019000309600_3.pdf">(part 3)</a>, p. 271.