RE: 1960's receivers
There is no such thing as an illegal receiver. Now, there was a change in the frequencies assigned to airborne radio control back in that time, just a slight reassignment of a few megacycles in the 75 MHz band. There is nothing wrong with the AM radios if they are using the legal frequencies. True FM and AM have different areas of problems but also have different areas of desirable characteristics. AM can still be and is a viable mode of operation. Now, some of the old "Wide Band" Am receivers are more prone to interference by nearby transmitter frequencies but are still usable in many locations.