The Briggs & Stratton 31R7070041B5 (15.5 Gross HP, 500cc) engine is compatible as a replacement for your original Briggs & Stratton ARIENS ZOOM 34 915131 & 915151 mower. NOTICE: If your engine model number starts with “31″, it indicates a 500cc displacement. Our 15.5 Gross HP, 500cc engine provides sufficient power to replace your original engine. Please note: Briggs & Stratton no longer rates 500cc engines above 17.5 Gross HP. If you’re comfortable with having slightly more or less horsepower than your previous engine, this model will be a suitable replacement. Briggs and Strattton vertical engine. 15.5 Gross HP. Cast Iron Cylinder Sleeve. 12 Volt Electric Start. Reuse your current engine’s muffler if the one comes with the engine does not safely fit your mower. Not for Sale in California. Consumer or Residential use. Commercial or Rental use. These numbers can be found on a plate of your engine. We have a lot of engines available. If the 24 hour period has passed and you have not heard anything from us, PLEASE try one more time. There might be some problems preventing your message from getting to us. Please leave us a message if the line is busy or nobody answers. VERY IMPORTANT: Engine(s) may or may not be filled with oil. PLEASE check your engine oil level and add oil as needed before using. We will not do it. Please look at the return condition we set on the top of this page. Please remember, if you send a request to look for an engine, it is our courtesy and pleasure to research on your engine’s fitness and specification for you. We use our best knowledge and experiences to answer all your questions. However, we are not responsible for your engine’s fitness, functionality or merchantability. It is customer’s job to assure that the engine ordered will work and fit for their specific application. WARNING: WORKING WITH ENGINES or POWER TOOLS SUCH AS SAWS, GRINDERS, DRILLS, CHAIN SAWS, AND THE LIKE, PRODUCE A POTENTIAL RISK TO THE USER. CARE AND CAUTION AT ALL TIMES SHOULD BE EXERCISED BY THE USER TO AVOID POSSIBLE LOSS OF PROPERTY OR PERSONAL INJURY OR DEATH.