New member with a rear brake issue

[gdawg]

I recently bought my sister's 03 z71 Tahoe. My right rear brakes keep dragging and I'm not sure exactly what the issue is. I've replaced rotor, caliper, brake hose. When I originally replaced the brakes on the rear, the right rear was almost gone and the left rear was only about half worn. Not sure exactly what to do. Is this a simple adjustment, possibly a defective caliper or what? It does have the drums for the parking brake too