The engine #s should be visible without removing anything. They will normally be just above the spark plug, stamped into the metal of the blower housing (the part the recoil starter bolts to). The problem I see with this engine is that the blower housing is painted the wrong color (should be white). This makes me think it could be from a different engine or possibly a new replacement. If it is the latter it won't have any #s. If it came from another engine it will be a tossup when trying to get parts for it.