My wagon has developed a noise that I have never heard before. Last weekend I was driving slowly up a rather steep grade (under load), when, from beneath the center console, at the area of the emergency brake, I heard and felt a series of hard sounding thumps. Maybe 3 or 4. When I backed off the accelerator, it stopped. It's done it a couple of other times mainly when I've accelerated kind of hard from a stop. It only happens under load. Any ideas, guys? wondered if it might be a bad transmission mount. I haven't climbed underneath yet.