Update; do not have the "tunnel effect sound" here, glad not running with this issue.
I reported before a knock sound at rear end most likely under the cabbing when on uneven roads, bumps…like exhaust tube or else knocking something in the rear. I adjusted the spare tire and the tools in the back but not change.
So far all other components are holding strong, we love the truck but for the money should be more solid and better quality.