I just got a 1970 El Camino last week. Driving it around the neighborhood, I'm hearing a strange grinding noise coming from within the dashboard. The sound seems to be located near the speedo/tach area or perhaps a bit further to the left. Both gauges appear to be functioning correctly. The heater fan is not running. It sounds like more like a plastic grinding than metallic. The grinding comes and goes; I don't believe it is speed related. This is my first experience with a grinding dashboard. Anybody have an idea as to what this might be?