Hi Barry,
For accurate markings, find an original photograph of WM20 in Canadian service and copy that. Motorbikes fell into a class of their own regarding paint and unit markings. Only experts will tell you the "Correct" colour for
Military Motorbikes and you don't really want to go there unless you want a factory new parade-ground pussy.
I also tried to get close to original markings for my Aussie WM20, I found many photos and spoke to DR's that rode them in service, all correct and all different. Best photo I found was of a bunch of Aussie MCs in Syria with Kangaroos painted on the tank, so wrong but what the hey!
You are correct in that the Brits and Very North Americans painted numbers on their front guards... were it suited them.
Some bikes had a single coloured band to signify a unit, except white which was on the front and back mudguard which signified "Don't run me over" when riding at night.
As for the "C" serial no. on the tank, it appears in a single line or sometimes with the "C" centred over the serial no.
Also, if your WM20 barely leaks oil it must be empty.
