I bought one of these Audiovox converters. They are from the 70's and are what an owner might have added at that time.
You tune your AM radio to something like 1400kHz (I use a preset button) and then tune the converter to bring in your FM stations. When you turn off the converter, you can use the radio for normal AM.
I have a Hidden Stereo under the passenger seat, modern sound equipment at a reasonable cost. I can put the remote in the console, totally out of sight. You aren't far from me, I live in Arbor Vitae