The one on my Lo-boy had been sandblasted but rubbing black crud into it made the stamped number readable.Urbish":r8s2nnul said:If the serial number is worn off or unreadable, you can get close with date codes (cast into every major cast iron part) and/or the engine serial number (stamped in the block, behind the carburetor, just under the tappet cover). You can check against casting dates here (note that some cast parts may have been replaced with one from another tractor) http://www.tmtractor.com/id/id_004.htm.