Canadian Active Service Force Routine Order 451 of 27 April 1940 specified instructions for marking military vehicles in service in Canada.
"3. All mechanically-propelled vehicles passed into service will be alloted a Department of National Defence Number".
The DND Number consisted of the last two figures of the year of purchase of the vehicle, followed by a 1, then by the vehicle number.
"5. The following marks will be painted on all Mechanically Propelled Vehicles:-
(i) Designation of arm of service.
(ii)Class letter.
(iii)Department of National Defence Number.
The marking will be painted, as applicable, on the outside of the door of the driver's compartment or, where doors do not exist, on the panel adjacent to the driver's seat. Marking will be on each side of the vehicle.
Motorcycles will be marked on the left side of the gasoline tank in convenient sized letters and numbers.
White paint will be used for the marking of vehicles."
Effective 15 July 1943, Routine Order 451 was cancelled and Routine Order 3493 was promulgated. A new DND numbering system was introduced. Vehicles other than motorcycles were to be consecutively numbered, irrespective of type or year of issue commencing with D.N.D number 50-001. Motorcycles were numbered consecutively irrespective of type or year of issue commencing with D.N.D. number 2-001. Class identifying letters remained the same. Unit designations were not to be used, markings were to be in the same location as before.
More info can be found at
http://mpmuseum.org/provostvehicle.html
If needed I can scan the original Routine orders.