Here's the photo - I had to scan it in two parts, as it was too big for my scanner.
This is the aircraft in the USAF Museum, Dayton, Ohio, and although the interior appears to be black, there is a slight contrast, more visible in my example, between the colour of the instrument panels and consoles, and the closed door on the port side. It's possible that this is Bronze Green, which is quite dark, and looking darker due to the lighting used for the original photo. Of course, it might have been re-painted black at some time too !