Weird noise from rear end after taking bumper and spare tire off.

Took my spare tire and rear bumper off the other day and now I have a noise.

Actually its a noise and a "clunk" it feels like there is a tennis ball on my passenger rear wheel, i can feel it hopping.

weird thing is, it only happens in morning and after work when the truck is cold, it also only happens at low speed, but once i get the speed up and the truck is warm it stops happening at low speed.

it is enough to make me concerned but i have no clue what the heck it could be! I checked the lugs, spring, shock, any suggestions would be great!?

I plan on taking it to a shop in the morning but i was wondering if anyone had any related experience.

 

I was thinking it might have something to do with the LSPV. Due to the weight loss?

 

So the differential is engaging posi traction due to the weight loss? That makes sense with what I'm feeling

 

could be from your leafs due to the weight reduction. probably happens when the car is warm because the leafs have been warmed up. metal acts different when its constantly bending as opposed to stationary