Locating depends on version of engine. On the older L heads most likely location is on the metal engine cover above the spark plug, but could be stamped into the flap above the muffler on vertical shaft engines. On the OHV engines most likely location is stamped into the valve cover, but I have also seen it stamped into the metal shield that wraps around the cylinder. Vanguard engines normally have a metal tag riveted to the blower housing normally between the flywheel and the spark plug, or could be on the side of the housing.
