I just noticed this lately as i was driving with the radio off and windows up. I have a constant type of squeek coming from the rear of the truck. It's not a bad squeek just always there and varies in severity on the type of road. When i get out of the truck i can hear them "give" and when i "get on" the back bumper and jump i can here them. Never notice them before. Anyone else experience this??? I guess i'll try some white lithium on the shackle hanger/bushings etc.?