I have a 71 Cuda and want to convert to retractable front seat belts like in the 73 and 74. Problem is, I would have to change the rear panels for a factory appearance, so I might just want to cut slots in the rear panels to retro-fit the mechanism. So if you have a 73 0r 74 Cuda or Challenger with these (OR HAVE ACCESS TO THE PANELS), where are the slots located on the rear panels? In other words, how far back from the lip on the panel and how far down from the window opening are the slots? ALSO, did the retraction control just the shoulder belts, or the seat belts as well (like modern cars)? Thanks in advance!