I believe that is a crystal operated scanner see this link: A demonstration of a 1970's Electra Bearcat 3 crystal controlled scanner. - YouTube
You will need crystals made for Bearcat scanners. Bearcat crystals are for a 10.8 MHz IF.
That is a great link! I can use it near future!! Thanks!!!!!!!!!!!!!!!!!!!!!!Scanner Crystals | Bearcat Regency Police Fire EMS Radio Scanner Crystal
They take internal crystals for each channel, the company above has the best stock.
In order to assist you, you need to review the RR DB for Sumner county and decide which of the conventional frequencies you want to monitor. I did not see any evidence of digital frequencies or trunking systems. So, this radio might work for you. My first police scanner was a Bearcat IV which was very similar to this model. One of the best features of this radio is volume.