Over the years Primo/Rivera have changed the construction of stock replacement Pro-Clutches, as well as Pro-Clutches as supplied with Brute Classic, Brute III, and Brute IV belt drives. The early style Pro-Clutch had a clutch hub with integrated steel rear plate, the late style Pro-Clutch have a hub and separate steel end plate. When using this replacement clutch pack on early style Pro-Clutch, the supplied end plate should not be used. Please note that Pro-Clutches used for stock replacement and the Pro-Clutch as supplied with a Primo belt drive are NOT the same!