The 1900s Pullman Coach's normal map makes it look as though it is made of steel, with distinct nuts & bolts representing the borders of steel plating. I'm spending a lot of time doing reskins of Canadian passenger cars, and most steel cars like this weren't made until around the start of World War One. Wooden equivalents, however, would have been made in the 1890s and this could offer more variety to players before the year 1900.

Unfortunately, I have no experience in making/editing normal maps. If someone could edit the normal map of the pullman 1900 car to look like it is made of wood, I will list you as a contributor to the mod on each workshop item I post that uses the edited normal map.