2019 Ford Raptor. Great shape etc. There is an annoying rattle or clunk under the bed in the rear. Sometimes If you hit a bump BUT MAINLY WHEN I MANUALLY.. jump on the back bumper and when I make the bed move up and down it makes noise. Sounds like spare tire is loose but when I get under it I can't pin it down? And unless something is inside, that I can't see above, loose etc it feels solid. Thought that IT was in tailgate but that has been ruled out. ShockS or spare tire needs dropped and checked? THANKS IN ADVANCE!