Tinny/metallic rattle/tapping only at highway speeds

HunterZ

Hey everyone,

I'm hoping someone can point me in the right direction for tracking down a rattle I've been tolerating for over a year.

The sound comes from the passenger side rear of the car. It's a rapid tapping sound with a distinct metallic note. Kinda like if you rapidly tapped a pen to a tin can at high frequency. The strange part is that it only appears at high speeds. It starts at around 60mph and gets louder with even higher speeds. This makes me think that its wind related and likely not inside the car.

A quick search didn't yield any previous posts with this described sound. Anyone else deal with a sound like this? Thanks!