I just purchased a 1975 450 SL and am having a problem with the radio.
The seller told me that the radio worked fine, until he had it repaired for
a blinker light problem. The radio turns on and lights up, and the antenna
goes up when I turn it on and goes down when I turn it off, but there is no
sound.
I looked under the driver's side dash and discovered a little box with a red
light and a switch, and a couple of other disconnected wires, but I haven't
got a clue as to what they are there for, or what to do with them.

Can anyone enlighten me?[8|

 

Well first off welcome to the forum.

Second i am guessing that the box with the light and the switch is some kind of security system.

But i can't help with the radio since i ain't there but u might want to pull it out to make sure all the connections are attached.

 

Welcome!