[roger_27]

pretty much any speaker will work. you don't need the original size at all! and speakers work no matter which way you have the wires. though you really should put the wire with the line on the negative, and the solid color wire on the positive to ensure the life of the speaker.

if no sound comes out from 2 different speakers, the problem will most likely be the radio.

I have no clue if 66 had vaccum tube radios or not.

I hope someone here can fill that in for you!

 

[ImperialCrown]

Speaker measurements are generally cone size, not fastener spacing. They were standard sizes and should still be available, although generally no longer used.
The speaker return would have been body common (-). You may have a green spkr (+) wire.
1966 would have been solid state.

 

[storm9c1]

Factory speakers on many old cars sometimes have weird fastener mounting holes. If you can rig up a way to mount a modern speaker, go for it. But make sure the ohms of the new speaker is close to the old speaker. For example, some transistorized radios might want a 10-ohm speaker. I would NOT use a modern 4-ohm speaker in its place without a 4 to 6 ohm resistor inline with it (which will unfortunately lower the volume slightly). It's best to find a 8 or 10-ohm speaker if that's the kind you need. I've also seem the opposite -- some factory radios need goofy things like a 3.2-ohm speaker. So look carefully for any printing on the speaker that indicates how many ohms. Lacking that, a 8-ohm speaker is always a good in-between guess. You could also research it online. I've found some good info as well as factory reproduction speakers after looking for a while on Google.

 

[TWX]

I've got an old unused aftermarket speaker like this eventually to go into the Cordoba, I'm either going to use it for a center channel if I go to a five-way speaker system, or for a ham radio speaker... They're still around, so you might be able to find something if you don't want to build your own mounting bracket for a different speaker.

 

[covertopps]

If you look at your factory speaker you will notice that it is narrow, and it also has a low profile. If you have an original AM radio it will be a 2 watt that uses an 8 OHM speaker. The profile of the speaker is to allow clearance for wiper linkage, under dash wiring and fresh air tubes. If you want factory size go to a company out in Minn called Electro Tech. They handle all kinds of factory size speakers and they really know their stuff. Cost is about 50.00 delivered to your door in about 3 days. Also some models like the late 60's B bodies have a speacial bracket that bolts to the speaker and then to the dash.