You will have to use the muffler and manifold, and stub shaft off of your original engine. If you replace the 303447 with a 356447 engine, you will also need to replace the flywheel, fan, blower housing, and starter gear with parts from your old engine. The flywheel fan and housing is 1-3/8" thicker on this engine than the 303447 series and the old parts are needed for fitment.
