I have the same exact problem with my 04 GT, when your in park and you crank the wheel all the way left or right you get a click noise (usually just one click) I have been trying to figure it out for months and I took it to get checked out and was told its my Rack and Pinion, was told sometimes you get a broken tooth on a gear and it will cause that noise. Gonna take it to dealer to see what they say..just to make sure. the car drives fine with no issues otherwise.