Please consider the iconic UH-1H Iriquois "Huey" helicopter, the troop carrier version is the 'slick' model, but you could include options for the other weapons that would turn it into a gunship. The Huey was a huge part of the Vietnam experience for the thousands of veterans that served in that place, as well as most every veteran that served in the 1960's through the 1980's.
http://vietnamphotography.com/images/0041.jpg