This engine has a 3/4" x 2-5/16" shaft on it and a 1/2" x 3/4" pto shaft. If you use the Lh195sa-67435 engine with the single shaft, you may be able to use your side plate and cam shaft of your old HS50 engine to make the new engine have a secondary pto shaft if your exhaust port is located to the right of the carburetor.