I have a 98 GT and on a cruise yesterday i hit a couple of hard bumps that i didnt see in the road. It was on the highway so i couldnt miss the pot holes. Anyways it only does it if its between 5-20 mph and it does not do it under a load. It does not do it all the time. When the noise starts it is a low tick or buzz. It comes from behind the speedo/tach area. When you pop on the dash with a little bump it stops. Any ideas as to what it could be?? Its driving me crazy