Well folks I had been looking for the wiring (plug) info for this radio for quite some time and finally found what I was looking for. So for those who have also wanted to use a different mic here's what I found. This info is for the the CRT SS-9900 which is simply another rebadged at-6666. Hopefully this helps someone else. P.s. stay away from the center pin as it is 8 volts and you don't want magic smoke!