Yes in those days most vehicles only had AM radio so people would buy a 8-track and install the 8-track in any place they could fit it in their vehicle and also 4 speakers.
I had a 73 Dodge Charger with only AM radio.
I installed a FM tuner and set my AM radio to a specific frequency on my AM radio and I could get FM radio.
The single button on the FM tuner for all the FM channels.
My next vehicle was a 1985 Dodge Daytona Turbo 5 speed and it had AM/FM and a cassette with 6 speakers.