Similar when I was in college (for automotive). A friend drove a Chevy Luv. He was actually pretty good, decent student and knew his stuff. One day at lunch he asked if I'd ride with him and listen to the rattle sound in his truck. He had it in a shop - they pulled door panels, looked high and low and found nothing. My friend had looked all around, emptied the glove box and everything else he could think of.Reminds me of a story my wife told me about when she was a kid. Her dad's pickup was making a clunking sound on acceleration and braking. He and the local garage tried everything to fix it but couldn't find the problem. One day long after he had given up on it she was riding in the bed and heard it. The truck had a piece of plywood on the floor (bed protection before we had liners and linings) and she heard it under the plywood. It was a bolt laying on the bed under the plywood that would slide to the front and go clunk when braking then to the back and go clunk when accelerating. Easy fix.
You described your sound as "something rolling around in the bed" but only when hitting bumps at low speeds. Have you had anyone ride in the bed and listen for it? At a minimum you might be able to narrow it down.
We used to do things like stand on the running boards and lean over to listen (50's era pickups), run alongside listening, sit by the bump (or whatever might cause the sound) and listen as it goes over it. Dash rattles often required someone (usually me) to get inverted in order to reach up and push and pull on stuff behind the dash while the other person drove. More recently I have used a GoPro to see a body mount clunking. I don't trust anyone else to diagnose clunks, rattles, and squeaks. Nine times out of ten it is "no problem found".
Try mounting a GoPro under the Jeep and seeing if you can see anything Is what I’d suggest.@Volt0 the service manager and 3 technicians were able to hear it. They were able to reproduce the sound. They apparently don't know where or how to fix it. They basically heard it and said idk.
Yeah, that's very helpful of them. Geez. But if it is going to take a lot of time locating the source, it might be more cost effective to locate it yourself vs having a shop do it (repeating the advice that has already been posted).@Volt0 the service manager ... basically heard it and said idk.