Seems to me like the big builders would all have a way of marking their engines so people can tell if they are getting a genuine engine from that builder. I know Welch used to engrave 3 numbers on the back of the block, just under the fins on the head where the head meets the block, i had one of his engines that had the numbers there as well as the welch racing stickers on the blower housing. If they arent engraving or marking them, what is to keep someone from swapping the blower housing from a good tod miller engine over to a junk engine laying around and selling that as a tod miller engine at a high price?