Accessing Radio Connection In a 1969 Valiant

Uggh. you never mentioned it was a thumb wheel radio. If there is a screw through the bezel just right of the wiper switch, remove it. It goes clear though that radios front support. If that screw isn't visible the bezel will need to come off.
I'm working from memory here. I cant recall there being more than 4 screws in the ashtray hanger. Unless you also have the 68 type dash with lower dash pads. That ashtray hanger is made different. Might be 2 more screws pointed left and right in that one. My memory sux. These situations are why I so often recommend buying the service manual for particular make/model.