Prince Rupert Regiment MG

[servicepub (RIP)]

Not quite. They wouldn't have had overseas markings but there was a marking scheme for vehicles of the Canadian Army - as opposed to the Canadian Army (Overseas) (CA(O)) - that remained in Canada.
Typically the door would be marked in three lines, i.e.,

P. R. Regt (or Pr. Rup. Regt.)
M
40-3-275

I don't have my references here at work but the first line is the official abbreviation of the Unit, the second line shows the class of vehicle, the third is the Cdn Army Reg Number. The latter changed at some point in 1941 and the meaning changed. Initially the first two characters represented the year (1940) in which the vehicle was acquired while the rest of the numbers represented the sequential acquisition number of the vehicle (3,275th vehicle obtained that year).
Although there was no AoS to Canadian Army vehicles the vehicle would show the formation (6th, 7th or 8th Division, or Atlantic or Pacific Force) although these came and went and careful OrBat research is required.