 Nevertheless, by the end of the war, roughly half of all operational Mustangs were still P-51B or P-51C models.In November 1944 the Australian government decided to order Australian-built Mustangs, to replace its Curtiss Kittyhawks and CAC Boomerangs in the South West Pacific theatre.The Commonwealth Aircraft Corporation (CAC) factory at Fishermans Bend, Melbourne was the only non-U.S. production line for the P-51.