Me and a couple of neighbors were talking about our tractors. Mine 4066R,one neighbor 4044R, other neighbor 5075M. We got to talking about the key for ignition if they would start each other tractor? Well I took my key out of my tractor and I unlocked the 4044R cab and started the tractor up. I went over to the 5075M unlocked the cab door and started it. So I take it that JD uses same key and ignition switch for the 4000&5000 series tractors? So how does one secure your tractor?? If anyone else has a key to these series of tractors they could start your tractor up and drive off. Not good. My neighbors keys did unlocked my cab door and started my tractor. Makes a person think.