96 power antenna (w/ cd changer)

I am getting the 96 Taurus ready to sell (bail out). Since the antenna broke, I bought a new one, but it is not a factory unit. ($$$)

I discovered that the factory antenna had a 4-wire hookup, and inside the antenna is a motor driver circuit board. What concerns me is that the control signals into the old antenna might be serial data and not the typical On/Off signal from other radios.

Has anyone replaced a factory antenna with an aftermarket antenna?

The 4 wires are labled (inside the circuit board):
+B....I assume positive battery
RX.....
ST.....
GND..Ground

I'm an electrical engineer, so I'm not looking for "guesses"; I could do that myself. I want to find out if I can tap into the wires without destroying the CD changer.

Thanks

I discovered that the RX output from the head unit does not have enough power to activate the antenna, but it is the correct wire to control the antenna (pink wire).

What I did to get the new antenna working was to use a power transistor (typical Radio Shack stuff) to amplify the RX signal.

A transistor has three pins; Base, Collector, and Emitter.

I connected the Base to the RX output (pink) from the head unit.
The Collector was connected to 12 volts from the head unit (green).
The Emitter was connected to the control wire to the new antenna (blue wire in most cases).