have a 69 b body with the factory AM radio and single rear speaker. when I bought the car the radio did not work meaning when you turned the radio power on you did not hear anything. car is now a part and i would like to trouble shoot this. What is the simplest way to test whether my radio, wiring, or the speaker itself is the culprit on the benchtop? have no spare radios or speakers lying around, but only my AM radio and the single rear speaker.