When I replaced my 351W starter ring, I put the flywheel in the freezer over night. Next morning I put the ring gear in the oven on its highest setting (500?) for an hour. When I dropped the ring gear on the flywheel I could spin it with my hand. 20 seconds later it was seized solid. Easy pesy.If you have never replaced a ring gear you must heat it so that it will drop on the flywheel.