I did the same thing on my 59. I had a passenger door that was all busted up. So rather than fight with it, I just mooched a good one. As it turns out, the one I mooched was off a 55. The 55s have a slightly smaller screw attaching the interior regulator cover. The 56 and up use a bigger screw and there are about 14 of them. I replaced all of mine with stainless. That's the only difference I know of between the early and later doors. So its more likely you get a door with bigger screws in it.