You need a torch. The old one will drive(knock) off and then you heat the new ring gear untill it just starts to smoke a little and place it on the flywheel, seat it in place and when it cools it'll be on there tight...Be sure to have the beveled/chamfered (I'm certain it has) teeth facing the proper direction. We used to get up to about 10 smackers to do it at the clutch shop.