Pinging Sound

I have a 2016 Tacoma Sport with 105K miles. The truck has served me well, never any issues. I've been keeping up with the maintenance on the truck. Just recently I'm getting a pining sound and it sounds like it's coming from the back of the truck. I hear it when I'm on the highway going over 60 MPS and the sound bounces off the wall (highway divider). The sounds does not go away if I hit the brakes and the pinging is constant. Meaning, the sound does not get faster or slower depending on my speed. Any Ideas?

 

Spare tire chain loose maybe? Exhaust hangar rubbers worn? If it’s not speed dependent, then wouldn’t be drivetrain related, I wouldn’t think.
I’d crawl under there and see if anything is loose

Edit: my old 94 Chevy had a similar sound. The spare tire chain had fallen down through the wheel center and would slap the rim. Drove me crazy til I figured it out. I’m very anal about squeaks and rattles