from what i learned on this site as i have a 52 and was wondering the same thing a while ago, some states used the # stamped on the ledge to the side of the distributor (now if the engine thats in the truck isn't the original motor, then you will run into a few problems with getting it titled/registered, most likely you will have to have them reissue you a title, comes with a new vin/serial #) and other states used the # thats stamped on the plate that goes in the driver door post. And thats the only 2 places on these year truck that can be used to identify it.