OK. An update. I took out the glovebox and felt around while someone else drove the car. I could hear the noise coming from the interior near where the windshield and the body meet. I can't find anything that is making the noise or exactly where it is coming from. So despite all that I've taken apart the noise is still there.
If anyone figures it out, let me know in this thread.

 

Has the windshield been replaced lately? Some years ago on another model there were some windshields installed at the factory slightly cockeyed and they were creaking on a support block when the body flexed.

 

I found the location of the rattle, but am unable to reach deep enough to locate it or stop it. Theres some loose metallic piece (maybe a long rod) moving around between the windshield and the dash. I've only been able to suppress the noise by applying felt tape to a piece of rubber that is next the source of noise. It applies pressure and keeps the piece from moving around too much, but it still manages to rattle on extremely bumpy surfaces. I don't really know how else to approach the situation because I can barely fit my fingers between the windshield to tape down the rubber, let alone find the source. I'm just trying to find better tape with stronger adhesives while pairing that with different techniques to taping the rubber.

 

The windshield has not been replaced.
Domm, good to know. I still have the a pillar cover and the metal(or plastic grill) off and I'll feel around. I fell the rubber that you're talking about but can't feel anything else. I couldn't supress the noise when I was pushing down on the rubber. Strangely, on really bumpy roads, the noise doesn't occur. It only seems to occur when there is a small gap or bump on a relatively smooth road.

 

Try lifting the rubber and pushing it towards the dash to see if it makes the noise. I had to tape the rubber up so it no longer contacts the windshield. It's kind of hard to explain.

Also, when trying to put the A pillar back into place, you can pull the insulation around the area where the A pillar meets with the dash to create space. The A pillar will slide in easily after that and the insulation can be pushed back easily.

 

In my case, I don't think it is the rubber because it becomes quiet when the interior is hot. What I did was stuff a felt cloth in between the rubber and the windshield and the metal under the rubber. We'll see what happens.

 

This is the all-time great rattle thread:

http://www.benzworld.org/forums/w204...anel-flex.html