I had the same problem with my '03. The factory ball mount fit, but one I had from an earlier truck didn't. There was some kind of recall on it, but when I took mine back they said my vehicle didn't fall in the proper VIN range. And because the factory ball mount worked, they wouldn't change it. I went to a NAPA and checked several of their Reese ball mounts, and found that some fit well and others didn't. I just bought the one with the drop I needed that fit and left it at that. I have a friend who also has an '03 V-8 and he has the same problem. The factory ball mount fits fine, but he has one of those hitch mounted cargo platforms which has to be persuaded (hit) in and out each time he uses it. His dealer also wouldn't change the hitch because the factory ball mount fit.