Yours is a 52' Merc and mine is a 53' Merc, so the radios should be the same. Hook the radio up to a 6 vole battery and use alligator clips with two wires from the plug to the radio to the two connectors on the speaker. Pick any old car speaker you might have around the house that still work. You will need to hook up an antenna to get a station. I have attached a picture. If it is going to work when you turn it on the vibrator will begin to hum, wait for it and see if you get a station. The tubes and vibrator are all still available. Tube chart attached. Bottom line is what I have found is that if the speaker is too big for the radio it just won't power it, but that said I have never found a car speaker that it hasn't worked with. You may have to turn up the volume but it still worked. Once you get the radio working, your next project:
https://www.fordbarn.com/forum/showthread.php?t=182556
If you need anything else my e-mail address is:
[email protected]