You don't have to use only a 9 tower clutch. You can use a newer 6 tower clutch. As long as its a 30mm bore (1:10 taper). I've used 3 different kinds of clutches in my EXT 550...the original one that came with the sled, then a Polaris P85 and now a New Old Stock 6 tower off a 2007 Z570.