The rear caliper does not need to be removed to access the pads, you only need to remove it if you want to remove the rotor. Hammer out the retaining pin and you will be able to pull the pads out. The bolt that you removed seperates the two halves of the caliper, you do not want to remove that.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record