Do you want to keep with the 120vac unit or do you want to go 12DC
I will ASSUME the latter.
YOu need to visit Crutchfield and fine the unit you want many options to choose from and I can not recommend any given make or model but that's the catalog.
NOTE: you may be able to shop locally after you "windows shop" Cruthcfeld
JR.Music is another catalog with many options
After that you need a box.. Wood is just fine
And you will need to add an automotive antenna
Thats about all there is to it. Connection is straight forward at least if you have done that kind of thing in the past (I HAVE)
Since you said "Talk radio" you night even shop for a general coverage Radio Receiver (they come in 12 volt desktop types) at places like DX Engineering but they tend to be mono only (not stereo) and don;'t do USB or CD
Mine does transmit though (Requires a license)