Hi Doug,

I am not familiar with the FSG60, but on some other radios, different pins on the harness plug are used for dynamic mics than are used for standard (or electret mics). Since you have the manual, you should check the wiring diagram to see if this is the case for the 60. If it is, that explain why it did not work when you connected it to the old jack wires. If the manual does not make this distinction, then some of the older radios have a potentiometer that you adjust with a screw driver for the gain required of a standard vs dynamic mic.

In terms of the mic itself, there should be two wires plus a ground wire. The ground is usually a shield or a bare wire. As far as the other two wires, it does not matter how they are connected as far as + -. Just like a speaker, it does not matter which direction the current flows through the mic. So, as long as you can determine the ground wire you are set.