Here is what you will need:
- 1 - "Whisper 2000" Hit garage sales or e-bay.
- 1 - 20 amp battery clip
- 10-15 feet - microphone cable
- 1-2 inches - vacuum line that fits microphone cable
Now, lets rip your new toy apart.
Carefully pry the speaker grille looking part off the front.
Next mark the wires going to the microphone so you will be able to keep them straight (might not be necessary, but it won't hurt), cut the wires and carefully remove the mic. The mic is held in with some king of hot glue looking stuff.
Remove the battery compartment door and the three small screws in the back.
Remove the guts and set aside.
Put the two case halves back together and mark the side for a cutout (slightly smaller than the vacuum line) for the mic cable. Using a file and filling two matching semi circles will
work better than drilling. If you drill the case you take the chance of breaking the posts that the screws go into. Don't ask how I know this.
Slip the vacuum line on the cable and strip the end of the cable. Separate the braid of the cable and twist.
Solder the cable to the mic connections on the circuit board noting the polarity.
Remove the cover from the clip and place on cable. Repeat the strip unbraid and twist routine. Solder the mic on (again noting polarity). Now hook a battery and the headphones up to the "Whisper 2000" and ensure it is still working. You did test it before you started modifying it didn't you?
If it works, reinstall it in the case and screw the back on.
Place the mic on the inside of the battery clip and stick in place with hot glue. Slide the cover over the mic.
Retest. If it works, you are done! I have not gave it a try on anything automotive, but if it works as good on a Jeep as it has with me playing with it it should work awesome.