Loose Object Rolling Around Behind Dash

Hello Everyone,

Long time viewer, first-time poster. A few months ago I picked up a 2007 Mustang GT Convertible from a private seller. Car was in great shape and still is. Had only 38,000 original miles when I picked it up. I am loving it so far. I have only a few light mods which are listed in my signature.

Right now I have been chasing down an interior rattle noise which is very intermittent and sounds like something loose rolling around behind the dashboard area above the glove box and behind the air bag.

I have done a multitude of searches on this site and across the internet to no avail to try to chase down what could be causing this highly irritating noise. Another member of this forum, nippywhiffle, did post about this noise, describing exactly what I have been experiencing. Unfortunately, the thread he posted in is closed and there was no resolution. Here is the most accurate description of what I am experiencing, as described by nippywhiffle:

"One major problem is what sounds like something rolling around in the interior of the car. If I accelerate, it'll roll back, if I brake (or even come off the gas), it'll roll forward, if I turn left, it rolls right, and if I turn right, it rolls left. It's not something under any of the seats, or in the glove box, or any door pockets/storage compartments. It sounds like it's on the passenger side. I feel pretty sure it's behind the dash... but it's hollow back there, so I don't know where. It does sound like it's rolling on plastic though.

One time, the dealership thought it was in the rocker panel... but that would be a metallic sound I assume, which it isn't, and I'm sure it wouldn't sound this loud.

I feel like a screw has fallen out of something, and is just rolling around now. It doesn't happen constantly... it'll happen when I hit a large bump sometimes, and it's like this object comes loose, and starts rolling around for a while. Suddenly, it'll disappear, as if it gets trapped (til next time)."

The full original post is available here: http://www.allfordmustangs.com/forums/2005-2010-mustang-talk/206075-rattles-driving-me-crazy.html

I can tell you all that I have taken off the passenger side door panel, reached in there, cleaned it out, but couldn't find anything. I also took a look under the passenger seat and made sure all wires were properly clipped into place. I also took off the glove box to see if I could find where the noise is coming from. Even when driving with the glove box removed, the noise is still there.

I really have no idea what could be causing this noise and it is driving me crazy. I wonder whether it could be something that fell into the HVAC vents/tubes that route air to the dash defroster, but it is hard to see anything in there without ripping the whole dash apart.

I would appreciate any suggestions that you all have. I have access to a fair amount of tools and I'm not afraid of taking apart interior pieces if need be, but I don't want to keep chasing dead ends. I look forward to your replies. Thanks!