+^+^, (I feel like I'm talking to the artist formerly known as "Prinz") but here goes. The gear box in my Viper makes the same noise that you're talking about when it's in neutral and my foot is off the clutch. I read in a Q&A section of the Viper Owners magazine that they make some sort of "additive" that when used is supposed to stop the rattle. If I can find the article, I'll post the name of the product. Or you can call a Dodge dealer, and see if they've ever heard of the stuff. I think it's a Mopar product.