The P-51D Mustang incorporated advanced features such as a laminar flow wing and an efficient radiator design, and powered by the Packard-built Rolls-Royce Merlin V-1650 engine, it demonstrated superior highaltitude performance. The P-51D was equipped with a Hamilton Standard propeller as standard but shortages of the propeller led to the installation of Aeroproducts propellers on some P-51Ds built at North American's Dallas factory, and these were distinguished by the designation P-51K. Most of the P-51Ks saw combat in the Pacific Theater, although some were also sent to Europe. In addition to the fighter role, some P-51s were equipped with cameras and used as reconnaissance aircraft. Such aircraft which were converted from P-51Ds and P-51Ks were designated F-6Ds and F-6Ks respectively.