The US-2B was a seven-place utility configuration with one seat (5 in the illustration below) well aft at the end of the avionics compartment, one (4) that blocked (!) the cabin door but was normally stowed on the left side of the fuselage only partially blocking the door, two (3 and 7) aft-facing passenger seats, and one (6) located on the right side of the fuselage atop the bomb bay.
Bill Spidle photographed the interior of warbird US-2B, BuNo136398 N8110X, at the Mojave Airport in May 2004.
Note that two windows were added to the right side of the airplane aft of the cabin door.
The US-2C was a conversion to the tow target mission.