Lockheed F-80 (s/n 44-85044, P-80A-1-LO) with twin 12.7mm machineguns in oblique mount, similar to World War II German 'schraege musik' <i>(Schräge Musik)</i> mount, to test ability to attack bombers from below.
USAF
<a rel="nofollow" class="external text" href="http://www.nationalmuseum.af.mil">National Museum of the United States Air Force</a>