Adding speakers / aux on factory radio?

Never messed with audio before. Can I seamlessly add two more speakers and an aux cable to a 1966 Charger factory A/M radio? Or do I need to do some extra work? I can't find a diagram for the radio to see what connections there are.

I do believe that there is only one speaker output on your radio. You could splice into it and add speakers, but you will not have left / right balance or front / rear fader control.

I'm not entirely familiar with that setup you have but in general when you add or splice into speakers wires or outputs on any type of stereo the ohms rating drops or increases in half or more depending on how many speakers you add and series or parallel will make a difference. In series, the ohms will increase.. 2 - 8 ohm speakers in series will be a 16 ohm load, if you added 2 more speakers you'd be at 32 ohm load. In parallel 2 - 8 ohm speakers will be a 4 ohm load, or add 2 more speakers and be very low ohm load. Plus, in most cases the amplifier is set and designed for certain ohms and can be damaged if not correct. If I recall, many stereos from that era are usually 4 ohms but check for sure..

I could be wrong but I believe you can use your existing speaker wire as an amp input instead of an aux cord then run all of your speakers off of it. Doing this would mean unplugging your speaker and routing those wires to the amp then feeding the speakers off of the amp.

Call the folks at Crutchfield, knowledgeable staff that can help.