Holes in the base of the dash on a 66--reasons?

[msg]

I know about the 2 smaller holes under the deluxe heater control being for the mounting of the control unit, but the 3 larger holes...the one on the driver side under the washer knob, the one next to the 2 small holes for the deluxe heater controls, and the 3rd over on the base of the glove box.

Also, the one under the radio area I wasnt sure about and couldnt find them in the assembly manual. Anyone know what they are for? Particularly the one under the radio, I was going to rig up a base bracket to support the radio since the ac vent box and speaker I have has crowded the top access a good bit to have the bracket come down from the top instead.