Thanks! It changed to MON right?
Yeah, but I don't what kind of timeline you're looking at. I have a couple listings for CIL cars in 1965 but honestly you have to take it with a grain of salt because it could just be someone using the old marks on the paperwork.
Unfortunately the ORER isn't any help because it doesn't differentiate between the two in the car listings.
CIL changed it's name in 1956. Anything post '60-62 I would probably have as MON but that could include CIL reporting marks just patched out to MON.
Jason