71 Dart 7 1/4 to 8 3/4 Questions

I'm not aware of anyone that is making reproduction ones, but that shouldn't really be necessary. They are not a wear part, so old ones are fine and can be made to look new with a little sanding and paint. If you post an add in the parts wanted section, I'm sure there are a lot of folks that can help you out. A lot of people with 10" drums on the rear remove their backing plates when they upgrade to the larger bolt pattern as a function of converting to disk brakes. Some move up to 11" rear drums off of a van or big car, and others go with the rear disk setup off of a Jeep Grand Cherokee. Neither of these moves can be done if you're keeping the small bolt pattern, which I assume your car has. I think you'll be able to get the backing plates you need for somewhere in the $30 range. There area a lot of guys on this site that are more than happy to help and provide parts to support other folks projects on the cheap. Let me know if you need any other info...