original gm radio

[DeputyDan]

So I bought an original GM radio for my 72 c-10. The problem I ran into is I have no idea how to mount it, or where to get the plug that plugs into the back of the radio. The radio has a small bracket on the back that looks like it should attach to something but there is nothing there under the dash to attach to. The front of the radio has two knobs with silver discs behind them but I don't see any way of tightening the radio down under the knobs. Anyone have any experience putting these things in?