1953 and earlier vehicles used the engine number for titling and 1954 and later used the VIN. My 51 Chevrolet Canopy Express had a Colorado title and, when I bought it in 2000, it had been changed to the VIN. I started hanging around my grandfather's Chevrolet dealership in the early 1950's and I remember the problems we used to have when you changed the engine. Generally, if you did it right, Colorado would give you a new number starting with COLOxxxxx in stead of using the old engine number, so most shops would stamp in the old number to keep from doing the paperwork. If you got caught, the world wouldn't end, but it wasn't any fun. I don't remember a time that GM vehicles didn't have a VIN.
