I put an auto in my samy, probally one of of my best mods I did. You dont need a body lift or have to cut the tunnel, you just have to spend about an hour with the stock scissor jack to widen the tunnel. Using the 4wd transmission with OTT's Kicker3 makes the install easy. It also gives you the bonus of dual cases and marries everything together so you have a smooth drivetrain, well worth the $600. Off road the automatic performs awesome, it just crawls then if you need some wheel speed just stomp on and it goes. I was concerned how well it would hold up, I installed a temp gage and the needle barley moves off the peg even after wheeling it hard all day.