[akqj9]

I have a 64 C10 with the thrift heater (one knob). I'm trying to take the core out to check it and I undid 4 screws that hold it in place. Each time I hear something drop like a nut or clip to thread into. I can't get the top off since there seem to be 3 screws on the back side that I can't get to without taking the entire until out. Do I need to take the glove box out to get to the bolts that hold the unit in?