Rolling Bowling Ball Sound

I have a 2016 Tundra TRD PRO with a 3.5" lift and 35" wheels. Lately I have noticed a rolling type sound when Im braking at slow speeds or taking a slow right turn, best way to describe it is imagine a loose bowling ball rolling around in the bed. The sound is not always consistent and only happens in those instances when it does, it seems like its coming from the rear. Its not a wheel bearing. I'm at a loss for what it might be, Im just hoping its not indicative of something semi-serious deteriorating with the drivetrain.

 

Have you pulled the rear diff plug and checked for metal chunks and fluid?
I’d check that next.

(eta - never mind, didn’t notice slow right turn).

I’d listen to Sean on the dust shields.

 

Needle bearing....or wheel bearing...

 

Check the dust shields for the brake rotors and make sure they aren’t rubbing the rotor. That can happen. It only takes a small tweak for them to rub when going around the corner.

 

Did you check in the bed. Maybe your friends put a bowling ball in there.

In all seriousness, check the spare tire to make sure it's snugged up and not hanging loose where it can bang around.

Good luck.