So when I'm driving or even coming to a stop I hear a noise from the rear as if there's something rolling/sliding around back there. Struts are good but I'm beginning to think it's my strut mounts(KYBs bout 3yrs old from wbody store) but the front strut mounts are fine.

What else could be loose or cause a loose sound in the rear(everything is tight from lug nuts up to strut mount bolts)?