I figured it out last night, it has to be removed with the support brace attached to it and then the support brace can be removed by removing the round nuts.The support brace is held on by two screws that attach under the gauges on the dash.
Here is what a '72 Ford AM/FM radio looks like with mounting bracket.
I noticed on the 77-79 models that it also needs to be unbolted from just above the ash tray under the dash.