1st order of business is to check if the MC rear piston tapered "thimble" recess has the recess halfway down for the neoprene retainer to lock into & that that piece is on the pushrod. If no recess then that is a PB MC. Eberg said if that is your situation then lock it (the pushrod) in with RTV which sounds scary at first blush but if Eberg is OK with it then it's good enough for me