Rear Backing Plates

Hope it is ok for me to jump in. Was just going to post a similar question about rear backing plates for my 72 Demon (8 3/4 with disc front). Are the small bolt plates the same for all years? I feel like I took A off of the car years ago but they had 2 1/4 shoes on them vs B which had the 1 3/4 shoes on them.

Thanks
Jerry