Just a tip on those Madison cars, and other with similar window inserts. I use a Dremel with a fine sanding wheel and take down the angle of that "snap nub" molded into the window insert... works like a charm for me. No more struggling to remove it.
I also use the self-adhesive heating duct foil tape on the underside of roofs (or to a window insert) to all sort of illuminated cars. Also has the added advantage of helping to reflect the illumination a little more evenly inside the car. Really helps out the aquarium cars with the single incandescent bulb.
For cars with frosted windows - no interior detail - I change the mounting of the light bulbs for passenger cars, so that the bulbs sit horizontal instead of vertical. Then I use a clear drinking straw cut to length for the entire distance between the two light fixtures. This also helps to spread the light through the entire car, even with just two bulb illumination.
