The first Mustangs taken on strength with the USAAC were outfitted as dive bombers as well as fighters.  Powered by an Allison which ran out of steam above around 14,000 feet, these aircraft excelled at low-level operations.  With the introduction of the Rolls Royce Merlin, the Mustang became a true world-class aircraft.  This early Mustang was photographed at the US Air Force Museum in November 2004.