There are many different auto dimming mirrors that you can install in your LS. The earlier compass mirrors used the 3-pin connectors which would work, but you can also use the newer compass mirrors w/ the 7-pin connectors by removing the 3 pins from your connector and inserting them in the 7 pin connector(both mirrors are wired the same).
Pin 1, is the 12 volt run circuit. Pin 2, is the ground circuit & pin 3, is the 12 volt when shifted in reverse signal. I have the compass/outside temp single display mirror that only reqiured adding 2wires out to the temp sensor and 2 wires to the driver's side auto dimming mirror.