I think you have a 39-40 motor. I would be very surprised if Canada introduced the larger bearings and longer crank before US production did. These changes were made when the Mercury was introduced.
Well the 51 Merc block is trash.
Gmanrides,
Is the "Merc" true ---4" stroke--merc pistons?
Gene Tulsa
That is indeed a Canadian block. The number cast in front of #1 cylinder will give a positive ID of what year.
38 coupe, it'll have the large dia mains, because it's got the long crank snout. All 24 stud engines with the long crank snout run the large journal cranks. If you find a 24 stud engine with short snout, it is the early 38 engine and runs the same crank as the later 21 stud engines [LB 36,37,38]