You don't need a special tool. I Squeezed my hand in from the muffler side with a wrench and used a long extension to undo the nut at the very bottom of the post. It's a bit of a hassle but you don't need a special tool. If you get a buddy to help it's much easier. I never had to undo the engine to complete this. Depending on the post, you will probably have to align the skis again. Look around on the forum.... there are a few posts explaining the process....... Just my too cents