It's common for a car that is sold new in a state that requires one license plate to not have a factory bracket installed on the car. Looks like an owner fabbed up a bracket from two pieces of aluminum. Looks fine, as a tag would cover that, anyway.
Am only radio is rare. I believe 1978 was the first year that the am, fm, cb factory radio was available. My NYB had one. Of course it didn't work, the original antenna was long gone and no NOS parts available on the planet. That radio had an automatic antenna which when you turned it on...the antenna automatically went up. There wasn't a antenna switch on mine. I have since installed a factory power antenna and manual power antenna switch (thanks Mr. C for the power antenna) and put a modern stereo (with a remote and a 40,000 color display that Stan just loves) and it runs my IPOD with 12,000 songs on it. All 4 speakers are high end Pioneer's that sound very good (even without an external amp).