Radio Question

That $172 in 1977 would cost you $792 today. Nice find especially with the receipt.
Motorola made one that was quite popular with public service vehicles since the Motorola dealer that installed the communication radios also was able to install and service the CB radios that were in the police cars back in the day. They used to use them to monitor the trucking industry and to also monitor for accidents etc. Keep in mind that in those days there were no cell phones and many highways also had roadside telephones and call boxes to call the police for accidents and breakdowns.

The first emergency call boxes in the U.S. were installed by the Gamewell Company of Newton, Massachusetts in the 1880s, according to the company's website. Those boxes telegraphed the location of the call to the central fire station whenever the lever was pulled.