Trumpeter's 1/48 KA-3B kit includes a bomb-bay mounted crew compartment, apparently to be used for a forthcoming EKA-3B kit along with external antennas. They probably relied on the following drawing in an aviation enthusiast's publication because there is no cabin in the fuselage of the EKA-3B.
The EKA-3B was a modified KA-3B (tanker), which was a bomber; the EA-3B was one of the so-called versions, A3Ds with the fuselage aft of the cockpit rearranged to provide a cabin.
For completeness at the risk of adding to the confusion, this is an ERA-3B, a photo-reconnaissance "version" modified with an array of radio/radar jamming equipment to provide ECM training for U.S. Navy warships.
For more details on the A3D/A-3 family, see http://tailspintopics.blogspot.com/2010/09/mighty-skywarrior.html