CFS3 default B-25J is a gun nose.
The B-25J was initially released as a glass nose bomber version. The transparent nose with its bombardier could be replaced at the factory by a solid nose that was equipped with eight 0.50-inch machine guns.
With this modification, the aircraft was designated as B-25J-11, -17, -22, -27, -32, or -37, depending on which production block the modification took place.
With its maximum armament of eighteen guns, the solid-nosed B-25J was the most heavily-armed attack aircraft in the Allied arsenal.

Since the B-25J is a gun nose with .50's filling what would be the bombardiers compartment.