Not sure about "Canada",
Came across this on ECR's site.. but I am no expert
In the US
"According to the D.O.T.: It is NOT
legal to import a vehicle as parts and assemble it in the USA and then register it for road use. This is a crime and is it NOT
legal. It is also NOT
legal to import parts that constitute a vehicle (such as 1 gearbox, 1 frame, 2 axles, 1 body) this too can be a crime if the intention is to assemble the parts.
Here is a NHTSA ruling on this: