I bought a '76 el camino with the 305. For some reason the overflow for the coolant is bone dry. Looks like it hasn't been used in years. It has a hose going to the radiator but the return hose is just a pipe going nowhere. The radiator is half full. I've had the car for a couple of months and driven it a lot and it's never overheated. Am I missing something or does this model not need the overflow?