Pulled off the pass rear strut a couple days ago to see what the noise was and it was the top of the strut mount contacting the body of the car.
New strut mount did not fix the issue.
What the hell would cause this?

I'm assuming the solution is to beat in the part of the body that's making contact with the strut mount??

Did you check the rear endlinks?

The top strut mount is supposed to be in contact with the body.

I cant imagine what is it you're saying that touches.
Can you post a pic?

Did you replace both the Strut and the Mount together or just the mount? It could be just the strut worn out but I think I'd replace the strut, mount and end-links all together if you mess with it at all.