C/W Pinion matching numbers

[john williams]

I have a selection of used C/W and pinions that were originally matched pairs. Over the years they have become mixed up. Yesterday I attempted to match them all up. Some have numbers etched on the back of the crown wheels, and on others I could not find any markings on the crown wheels. All of the pinions have numbers stamped onto the pinion shaft. Where else could the crown wheels be marked?  They all appear to be RP or MKI Ruby sets.