The PTO is balanced. It only goes on one way. Remove the half that is under the machine and look into the end of it. You will see a space that is wider that the rest of the splines. Now look at the end of the half that is on the deck. You will see a small spot weld at the end of two splines. Line that up with the wider spacing in the other half. It came from the factory with red arrow stickers to help locate the right place to slid it one.
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