Feel a Weight Shifting When Braking etc

Hi folks,

Lately I've been feeling like a weight is shifting around when braking or offroading over rough terrain. I thought the spare may be loose but it's tight. The bed appears secured to the frame. The bed was loose once before but it just rattled. I tightened it up and no issues after. It feels like there's a tire rolling forward and backward in the bed but to a much lesser extent. Anyone have any ideas?

Thanks

 

Make sure your ubolts are tight. About 85ft lbs I believe.

 

Fuel tank straps?

 

Axle wrap? Pretty common on our trucks

 

If it’s when off-road, gotta be the ice chest with beer in it for sure.

 

Removed the cooler full of beer but still felt it. Figured it out after, the driver-ride rear Icon shock is shot. Needs rebuilding. The shifting I am feeling is the leaf spring with no working shock.