When I start up my '63 Impala every couple of weeks this time of year, to give her some exercise, I sit inside and wait for the engine to warm up for about 5 - 10 minutes. Once that is done I turn on the heater and head down the highway. But, every now and then when the heater fan turns on I'll notice some little dark-colored chunks of foam-like material fall out from under the dash. Does anyone know what that stuff might be? Perhaps some kind of original insulating material hidden from view up under the dash?
Appreciate any thoughts from you folks.