The variants were the A3D-2P (RA-3B), A3D-2Q (EA-3B), and A3D-2T (TA-3B). Some A3D-2Ts (and reportedly an EA-3B) were outfitted as a transport and at least one was converted to an EA-3B. Subsequent repurposing of the RA-3B resulted in the ERA-3B.
The A3D-2P was easily recognizable for its camera port fairings and the single porthole on the side of the fuselage. The A3D-2Q had three windows and a door on the right side of the fuselage; there were no windows on the left side of the fuselage as the left side of the cabin was filled with consoles. The A3D-2T had four windows on the left side in addition to the windows and door on the right side.
As it happens, all of the variants were built with provisions for all the windows on both sides of the fuselage with the exception of the A3D-2P. It is likely that on them at least the third window going aft on the left side and the door on the right side were deleted during the redesign to reconfigure the aft end of the cabin as a small bomb bay. It's possible that provision for the aft window opening on each side of the fuselage was also deleted but an early Douglas access-panel drawing has it present.
Some have questioned why the versions were all built with the window provisions, some of which were then plugged. The answer is that metal airplane structure is made up of bits and pieces. Every one is created using patterns/dies (aka tools) to cut it to size, bend it to shape, drill holes in it, inspect it, etc. More tools (aka jigs) are used to combine parts into assemblies and so on. As a result, if the weight penalty is small enough, in order to minimize nonrecurring cost and to some extent take advantage of the learning curve and minimize investment in spare and repair parts inventory, etc, when an assembly is to be used for multiple applications, the lowest common denominator configuration is designed and then modified as required. There were other production control benefits as well,
Others have questioned that there were provisions for windows when none are apparent in photos of the airplane. The answer is that putty and primer obscure the presence of the frames and inserts, particularly if the pictures are not very high in resolution.
This is a picture of the left side of an EA-3B undergoing a major overhaul, stripped down to bare metal.
Angelo Romano
This is a picture of the right side of the fuselage of an ERA-3B. The outline of the window frame aft of the porthole is faint but definitely present on the original scan.
Rick Morgan
