the glass clamshell is for prisming the lights from a stop light, so you don't have to look up and crane your neck, remember that the windshields were a lot more verticle back then instead of aerodynamic and laid back like todays cars... it wasn't as easy to look up at the intersection lights if you were the first at the stop.
The other thing?
That thing on the dash board just above the headlight switch is a sensor for the automatic dimming headlights. It sensed the headlights of an oncoming car.
John D. Weimer emailed me to let me know, Thanks! 3 years and no one had filled me in about that!