Checking part numbers is sort of a last resort. Many of the part numbers were used over a number of models and years. (heads, power packs, flywheels, etc.) With lack of any real identifying info, it's a good place to start-but does get confusing with part number spanning a few years. Also, pictures of the engine and esp the cowling (paint, decals, color) are helpful if the engine has the original cowling and paint scheme.
