2004 Nissan Titan parking breaks

I went to replace rear breaks and removed rotor to see what the condition was with the parking breaks. I wanted to adjust them because when I try to engage them there is nothing. Truck will just roll if not in Park. Opened them up and there was nothing. No shoes, no springs, no cylinder to force pressure out. Nothin What should I do. Would this pass inspectionin Pa. I replaced the pads. I just bought it privatly.