Hi, I have a Canadian made 46 GMC 3/4 ton and had the same questions when I got mine (as it didn't come with any of the original motor or drivetrain). The canadian built GMC's used the 216 so they also used the chevy gauges, and they had wood bed floors (where the American trucks had steel floors). They also had a smooth tailgate, rather than the stamped GMC tailgate, as far as I've found.
Something you may find nice in your disassembly is that while the Chevy's used clutch head screws, the GMC's used flat head stove bolt screws instead. Hopefully yours is this way, so you don't need the specialty tools.
Those are the main differences I'm aware of from my research.
