There were approximately 225 Birds built from 1929 thru 1931. The "A" model was powered by the OX-5 engine, the "BK" model used the 100HP Kinner engine and the "CK" used the larger 125 HP Kinner engine. In addition, they also had several individual models. One had the Packard diesel engine and another the Jacobs radial engine. Currently, there are approximately 12-15 Birds that are flying or flyable. I restored and owned an "A" model for the past 15 years but recently sold it to the WAAM Museum in Hood River, Oregon where it will be used to hop rides. Steve Krog