Does the light wire from the radio go right to the headlight switch or does it connect to a wire thanks

I am trying to wire up a radio on my 1955 ford and I found a empty wire that was cut that is hot when the key is on but I can't find out the wire for the light on the radio. I know that has to wire in so when you turn on the headlights the radio lights ut. Also my radio has a knob in the center of the round face for on off volume but not sure where the station tuner knob is there is one knurled dial below flush with the radio is that it or is that for base and trebble thanks