what do you replace during a brake caliper rebuild/overhaul? and how dificult is it?

 

Replace all the rubber pieces. Piston seals & dust boots. Probably the seals around the caliper slide pins & around the handbrake shaft (rear caliper). Anti-rattle shims & little stuff like that.

Often new bleed screws, depending on corrosion.

But... if the piston or cylinder bore are scratched, you have to replace or hone or whatever. That's the part you aren't going to know until you take it apart.

The front ones are easier because there isn't any handbrake auto-adjust mechanism inside the caliper.