On the right...
...is the outside skin of the cab compartment which runs the length of the cab from front to back between the windshields. there's an alley between the right and left sides of the locomotive. It's "H" shaped (to a T). There are doors in the alleyway to let you access the motor compartment and it traverses the length of the body. I didn't have a flashlight so I don't remember much except "black".
Anyway, here's a closer shot of the cab stand.
Mind you, I am 6'-3" and yes SIZE does matter- I couldn't walk down the narrow passage without twisting my shoulders sideways and take sidesteps.
Pretty kewl- I always wanted to get inside of one of these- thanks to my friend Blake- we managed all 10 that were parked in Kearny, NJ at NJ Transits loco shop just after they were retired. The photos are dated Jan '84.