I have a Model 36 with a serial number that does not appear correct. It is 837JxxYY. The first six characters are normal Smith & Wesson stampings. The last two characters are numbers and are larger than the first six. I have no idea if these were added at the factory for some reason or by a previous owner. I think the first six are the "real" and complete serial number but my computer crashed and I lost my S&W serial number list. I would appreciate any help or opinions on this. The gun is a two inch square butt and is only in fair shape but will be a good shooter. Thanks in advance.