Have you considered rolling up the windows and turning radio volume up a bit???
A bit of reality. You have an old truck with many, many, many miles with delayed maintenance. As with all mechanical things, they age, they get rattles, vibrations, worn out parts, loose fasteners, hard bushings,..........................
While I was in high school, one of our click had an old beat up truck. He put a set of Baby Moon caps on it. Well, after listening to his constant brag droning on for weeks......we decided to make an adjustment to his bragging. A few marbles, hex nuts and some gravel in the Baby Moons had him hunting for the slow speed rattle for a couple weeks. He discovered the prank when he was changing a flat tire.
My point, some rattles are nothing but the vehicle showing age and mileage. Some rattles can be harmless pranks.