From Joe Baugher: 

Douglas XA-26D Invader

The XA-26D-DL (44-34776) served as a prototype for the proposed A-26D version of the Invader which was to have succeeded the A-26B on the Long Beach production line. The XA-26D-DL was powered by two Chevrolet-built R-2800-83 engines and featured a nose with eight 0.50-inch machine guns and a wing with six 0.50-inch guns. The contract for 750 A-26Ds was cancelled after V-J Day. However, the eight-gun nose tested on the XA-26D was later adopted for the B-series and the six-gun wing was adopted for both the B and the C series.

Serials of XA-26D:

Serial Number: 44-34776	
Model: Douglas XA-26D-DL Invader
Construction Number: 28055

 

Sources:

  1. United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian Institution Press, 1989.
  2. McDonnell Douglas Aircraft Since 1920: Volume I, Rene J. Francillon, Naval Institute Press, 1988.
  3. American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.