This engine has a 1" x 3" shaft. If you purchase one of the stepped shaft engines with the sleeve, you must make sure that your pulley does not have a key built into the pulley. If your key stock is built into your pulley, the sleeve will not work for you. In this case, you could possibly buy another pulley with no key stock on it. The shaft would be 3/16" shorter but this should not pose a problem.
