Impact air tool but not everybody has one of those in their back pocket. The old shade tree mechanic would secure the flywheel from turning. It could be a two man job as one is on the floor and the other over the engine. Just be sure to torque the bolt to the correct amount. I'm on the road today but the torque values should be in your owners manuals. If you have lost yours you can find them on our website on the bottom of the page where it reads manuals. You really don't want that thing to come lose while it's engaged.