Type AR
3 piece rim, has a square cross section lock ring visible in the photo
You can see the gap of the locking ring

And if that’s a Canadian truck it would be the expected rim at the time it’s virtually the only type I’ve ever seen on these trucks up there in that time range.
Two part rims popped up more later
I also own the widow makers but can’t say for sure which vehicle they came to me on at the moment
But the AR is the most prevalent
-s