Question re: CNW wood waycars


jonnyo55
 

I’ve noticed that some C&NW wood (cupola type) waycars featured a number board type appendage along the letterboard, right above one of the side windows on both sides.  What was the purpose of this device? Was there a specific number series for waycars so equipped? Were they removed after a certain date?  ANY info would be appreciated!

John OConnell