DC-3 was the civilian version of the C-47. They were also used in Vietnam, fitted with Vulcan mini-guns, known as "Puff's" after Puff the magic dragon. An friend of mine flew one of the first three to be sent there. He said firing the side guns would push the plane, and he had to compensate. He also claimed the guns were capable of putting a round in every square foot of a football field on a single pass.