Can't help with the source but the jeep itself appears to be a very early production Willys MB. The first roughly 3000 slat grill jeeps had short (lower) windsheilds which can be identified by the narrower sheetmetal skin below the glass. Dates the production of the jeep to mid-December 1941 or earlier.
Course even an early jeep could have still been in use during the Korean War so the date of the jeep won't help any. Still interesting that Canada got some of the really early models. Possibly the USA allowing someone else to work out the bugs in the new vehicles