Not sure if my issue is the same as what you describe. I have a unknown sound in this same location, right side, upper dash or lower windshield, but it sounds more like an air leak or wind issue, rather than a rattle. I first thought it was a rattle but then noticed it came and went with changes in wind speed and direction. It only happens at 55mph or greater, but if there is a tailwind it goes away and a headwind or sidewind makes it worse. I asked my dealer if he has ever seen issues with the windshield not being completely sealed and he had not.
---------- Post added at 08:19 PM ---------- Previous post was at 08:04 PM ----------
Probably the gray styrofoam around the hood hinge under the hood. Spray it down with silicon spray or WD40 and wipe it down. I know, sounds strange but the noise translates into the cab. Many have had this same issue. Repeat every 6-12 months.
I just went to look at this gray styrofoam and it looks like it could be the cause of the noise. It just sits in there, somewhat loose, and the plastic connector that holds it in was only halfway pushed in. I took it out and gave it a spray and wipe with Tri-Flow, hopefully this fixes the noise.