2 Radios plugged into 1 Speaker?

Well I used to repair OEM radios for Ford GM & Chrysler as well as for Audiovox. The answer is yes it will work but it may through the impedance of the speaker off. Typically you want an impedance of 8 or 4 ohms.When you connect anything in parallel be it another speaker or the second leads from another radio your are going to lower the impedance. For example if you have two 8 ohm speakers in parallel you will have 4 ohms of impedance. So the answer is it will probably work but the impedance will be off and your radios won't perform as well. Try putting a single pull double throw switch on one of the speaker leads going to the speaker with each radio connected to one of the other two terminals.

Good Luck