Simple radio install question

71 Demon 340 AM radio installation question. The car has the rallye dash. I'm reinstalling my original AM "2-knob" radio. (It was out while I worked on other things in the dash.) I'm questioning what holds it in place in its mounting location. It has the little single metal bent brace that attaches to the right rear of the radio and then to the lower edge of the metal dash. Each knob shaft has the threaded shaft but I don't see any of the typical thin nuts to thread on and clamp it to the metal dash. The plastic instrument panel (IP) will go over this and then slide the plastic knobsonto the shafts. But I don't see anything that would then clamp it to the plastic IP meaning the radio is supported from the rear but not from the front.

What am I missing? The thin nuts to thread on the knob shafts? Something else???

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