Hi Ya-all, Can anyone tell me the size of radio speaker that fits behind the dash board speaker grill on a 51 or 52 F1? Thanks, I am putting in a stock radio into my 52 F1 and it never had a radio so I don't know. Thanks! John

 

John,
I just installed a refurbished factory radio in my '52 F3. Here is what I learned. First, however is I believe the speaker was a 6x9 8 ohm speaker. I did not have any luck finding the dimensions of the rear and speaker brackets. 51 Panel Man has some great pics of the mod kit that allowed radio install in the trucks.
In my case, I had to move a heater cable to make room for the radio in the intended factory spot. With the heater hoses, wires, etc. I couldn't see how a speaker was going to fit above the radio. So, after installing the radio, I pulled the passenger side kick panel and installed an 8 ohm 6" speaker there. I cut straight grooves in the panel approx. 1/8" wide in a circular pattern. Then I obtained antique speaker grill cloth and glued that to the inside of the kick panel..mounted the speaker and hooked it up. The grille cloth behind the panel looks good, stops dust and allows good sound.
There is plenty of room behind the speaker so the magnet does not contact the truck metal. I'm fortunate in that the radio plays beautifully without the need to add noise condensers anywhere. I also installed a factory type antennae on the passenger side cowl near the fender. All looks good and plays well.

 

Thanks, For the input! I sold my parts truck that had a speaker in it (behind the grill) (Never sell parts trucks). I am thinking a 3"x6" will fit. Does it have to be 8 ohms? My truck I am building is still going to be 6 volt ,positive ground. Thanks again! John

 

Yes, 8 ohms. The voltage of the truck isn't the important part (mine is 6 positive ground also). The impedance of the radio to the speaker is important. Back then, just about everything was 8 ohm.