How do you ID old wood & cardboard rolling stock

Ray,
About the only way to identify those cars would be to find some late forties,early fifties MR or RMC, and check the ads to see which kit manufacturers released what road names. As I recall, those kits didn't have trucks or couplers included, which is why the one would have Varney trucks, and Mantua couplers. I also seem to recall that preprinted car sides were sometimes published in the modeling mag's.
Pete
 
I've seen one old "Megow" kit in the box, and it had trucks included, but the side frames were also punch out cardboard, and the axles were just fins brass wire that punched through both side frames to make up the trucks. Anyone who had one of those kits and wanted to use it on a layout would probably want to change the trucks.