Hy guys, P.T.O.s are transmission specific, first you must determine what transmission is in the f@#d you bought, then you can call your local truck wrecker and get the appropriate one. You may be able to swap just the correct drive gear into your SM420s P.T.O. housing, there is some interchangability of gears within a given housing, some P.T.O.s require a spacer between the transmission and the P.T.O., ask the wrecker to supply all the parts required to install the P.T.O. onto the transmission, hope that helps.
