I've had a set of wheel cylinders for my '74 'Cuda for a few months. When I went to install them, I realized that they were the wrong ones. They're supposed to be for my car, but the bolt holes don't line up with the slots in the backing plates. As it turns out, later-style parts do, for example, the ones for '75-'83 Cordobas. Any ideas on this? Was there a mid-year change in '74? My car was built in November of '73. Thanks!