Car is a W123 coupe, 230CE, 1981 model year.

Originally discovered this problem shortly after I got the car and did a teardown of all the wheels to check condition of brakes and suspension.

Passenger rear brakes would squeal at low speed. When I took it apart to investigate, I couldn't get the pads out of caliper. Removed caliper and found the pads were split, and half the friction material was stuck to the rotor. Well, that was obviously the source of the sound...

Replaced rotor and pads. Noticed that wheel was a bit harder to turn by hand that the opposite one. Then started to watch that wheel since split pads is sign of heat buildup. Noticed that that wheel hub was slightly warm after driving. Not hot, just warmer than the other 3. Even after 20 mile highway drive still wasn't too hot.

Drove like this a few months, I only go 3 miles a day most days.

Finally got around to replacing both rear calipers, assuming that one was sticking a bit. Also replaced the soft brake hoses to both rear calipers. Fluid came out pretty readily when i disconnected the hoses

After replacement, everything was about the same as before. So I backed off the parking brake on that side so that it doesn't even engage. Still the same.

This leads me to believe it is not related to the parking brake or the primary braking system.

What else would make the right rear wheel drag a little bit and to build up heat? Bearings? Something else?

Thanks in advance!