Thinking about changing my rear pads myself, how difficult is it?

 

As long as you can get the rear wheel off the ground at least 8" it is no big deal. Just keep track of which side of the axle the spacers belong.

 

Not sure on an 03, but my 98 ultra has a two piece caliper. 1 bracket, 1 caliper. Remove 2 caliper bolts, pull caliper from bracket, remove old pads, compress caliper with c-clamp, install new pads. Replace caliper in reverse. Do yourself a favor and get some brake grease for the sliders, and torque to spec.

 

You shouldn't need to pull the wheel. If you want to work on your bike, go to the dealer and pick up a factory service manual. It will pay for itself

 

Plenty of vids on YouTube with tricks and tips for the rear pads.