Aircraft were constructed by a three firm consortium, Boeing, Vega and Douglas, known by the acronym BVD. Boeing built airframes at their plant in Seattle, Washington and their production models were appended -BO. Douglas Aircraft Company constructed airframes at Long Beach, California with a -DL suffix. The Vega Aircraft Corporation, a subsidiary of the Lockheed Aircraft Company, at Burbank, California, delivered airframes with the -VE suffix.