Surfcaster

My 2011 grand cherokee(3.6L 4wd) laredo needs the rear propeller driveshaft flex coupling disc replaced due to cracking around the bolt holes. Anybody know where I can purchase just the flex disc?? The dealer parts guys tell me there is no separate part listing for the disc...that to get the disc a whole new driveshaft needs to be ordered..WTF? nothing available aftermarket..any idea where/how to get just the disc?? Thanks for your help