I just purchased a John Deere 318 which by the serial number was built in 1992. Ultimately was going to use it for garden tilling. On the rear pto is a pulley mounted with a bracket onto the pto shaft. First does anybody know the purpose for this seeing as how I can not find it on any parts list so far. Do I need to install the 3-point set up or is there a different tiller I could use. Thanks