I've got a 1949 Plymouth (of course). The car is in excellent shape, one thing is that the old radio doesn't work. I took it out of the dash to try and figure out what was the matter. I know a little about the old tubes and tried to make sure the filaments weren't burned out, they seem to be ok. I did notice that the power plug that goes into the side of it tested at 12 volts... but the car is still 6 volts... the radio doesn't run of 12 does it??

Here's the link on this website to the radio manual for the '49 radios.

viewtopic.php?f=39&t=1008

IF IT IS THE RIGHT RADIO IT IS 6 VOLT IF YOU ARE RECEIVING 12 VOLTS SOMEBODY EITHER UPDATED THE ELECTRICAL SYSTEM OR INSTALLED A UPVERTED INFRON OF THE RADIO
ARNIE