Rear Brake calipers are not centered on disc so outer caliper drags discs.  I just bought my first C3 74 coupe with 454 big block.  The calipers actually look pretty new but I don't know how to adjust this.  One side (passenger rubs worse and already ruined disc.  Front is more off center than rear of the caliper and drags worse in left turns than right.  Any suggestions?

I'm wondering if an extra shim/washer is installed on the bearing moving the hub outward? I had that happen once when on a front wheel car the did not press in the wheel bearing enough.....but that's a different animal then the rear bearings you have.

MR, I have only run into this once when replacing a rear caliper, the mounting tabs of one of the rebuilt calipers I was installing was cast too thick. I simply exchanged it for a new one and that solved the problem, unfortunately it doesn't sound like you have that option. Do a search and look for a posting on the Corvette Forum called Caliper is off center, need advice. It's from 2008 and there is some good discussion there regarding three possible causes - 1. Thickness of the caliper casting as I mentioned. 2. Bent mounting tabs on the rear carrier and 3. Rotors mounted wrong font to back. Rotors are easy to check with the wheels off, there should be an access hole to adjust the e-brake shoes, if not that might be your place to start. They also mention taking the calipers and switching side to see if the situation improves. My next suggestion would be to remove the rear calipers to make sure that someone did not install any type of shims that would move the caliper inward. It is rare but I've heard of people having to shim the caliper for off angle and off center conditions. While the calipers are off, inspect the mounting tabs on the carriers to see if the appear bent or deformed in any way. The mounting tabs are also cast so straightening them may be difficult, they might have to be replaced. Welcome to the site and I certainly hope your problem is part of one of the easier solutions. Look for further input from other C3VR members, I'll probably get put on probation for pointing you to another Forum !!

   What's the possibility it is mounted on the wrong side of the car?, or wrong wheel?

Possibilities are open to anything really.  The guy that I bought the car from owned a dealership and bought the car back from the original customer (buyer when new in 74) over 20 years ago.  He did this with many cars and it has only been driven a couple of times annually since.  The calipers looked clean and the hard lines new so I'm guessing they were put on about the same time as the tires that were on it.  The tires looked barely used and no cracking but the manufacture dates on them were all various weeks of 1982.

Neither the calipers nor the rotors are interchangeable from front to rear on these cars. Rear rotors have the parking brake integrated, and the calipers are completely different. Calipers CAN be installed on either side, but will only fit/work on ONE side, due to the brake line fitting & bleeder locations.
Chances are the rear calipers were changed, and the ones used were some off-shore copies that are not machined correctly.
Another real possibility is that the rear bearings are loose, allowing the rotor/hubs to "lean", causing the calipers to hit like that.