The last wartime version of the Kingcobra was the P-63F (Model 43). It differed from the P-63E in having an extended vertical tail for better control in addition to the ventral fin extension. It used the Allison V-1710-135 engine of 1425 hp instead of the similar-powered V-1710-109 of the P-63E.
The first P-63E flew in April of 1945. Only two were built (43-11719 and 43-11722) before postwar cancellations brought further development of the Kingcobra line to an end. It is not certain if the P-63F was actually intended for production, but it was used to test the tall vertical tail meant for the P-63E-5, which would have been built in large numbers for the Soviet Union had the war continued past May of 1945.
One of the two P-63Fs survives to this day. After the war, P-63F 43-11719 was sold to a commercial user, and in later years it passed though a succession of owners and carried numerous civilian registration numbers. It was at one time used extensively for unlimited racing, although without very much success since it was modified very little from its stock form. Bearing the civilian registration NX1719, it finished tenth in the Thompson Trophy races in 1946. It reappeared in airshows during the 1970s, painted in bogus Soviet markings. It finished fourth in the 1976 Mojave Races. It is now owned by the West Texas wing of the Confederate Air Force and is still flying as N6763.