Lionel Commodore Vanderbilt Std Gauge Engine Question

Tim, your question got me thinking, so I went and looked at mine.  I haven't "opened up the engine" as you have, but if I turn my engine upside down, there is a red bulb in the floor of the cab, pointing down over the trailing truck.  I had to remove the large screw holding the trailing truck in place and take off the trailing truck so I could get my fingers in there to remove the bulb.  It's a bayonet-mount red bulb, pretty standard, looks like a  363R maybe, like here.  I didn't see any red celophane, but then I didn't have my engine opened up the way you did.

Yes, that's the ash pan light. When you look into the cab, you will see the red cellophane in the firebox door. Just seems to me there should be a light shining through that too. Maybe I have this all wrong.