Neil, the M135CDN was used by the Canadian military for three decades so the vehicle type has carried a myriad of markings during its lifetime. The markings on the door of the vehicle in the photograph you provided is the Canadian Forces tri-service badge. This was a decal that was produced in various sizes to apply to the doors of vehicles that were generally considered to be used for non-tactical purposes, although they were certainly used on some of the SMP fleet, which I suspect were vehicles held by schools.
I always recommend using a photograph as the basis for any vehicle markings but at the same time knowing what the markings represent and the era they were used is also key as I have mentioned, the topic is very broad.
