I was looking at my rear calipers, they say PBR, not sure if this is a aftermarket brand or stock.. They are not, or dont seem to work very well.
my rear rotors are not real shiny like the are contacting. One is even leaking.

 

PBR is the stock rear caliper and they are a good system when functioning properly. You need to pull the brakes apart and see what's up (glazed pads, frozen caliper, verify the source of your leak - could be from the axle).

 

Are these rebuildable????

 

Yes, you can buy a rebuild kit.