If anyone's familiar with the Tell Tale Heart from Poe, then you know what it's like to hear that knocking. For me I hear it when I'm in park. It's worse when the truck is cold, but I can still hear it after truck is warm. But again, it ONLY happens when I'm in park. It sounds as if it's coming from underfoot. In fact, I can feel it if I put my foot on the floor. This might seem like an all too common porblem, but it's new on me. Any thoughts?