If I had to guess I'd say one is for manual and the other is for auto transmissions. You would probably also find that there is a TCU input signal from the one without the shift light.
Also don't forget the OBDII info is stored in the ECU, if this ECU was a holdover from before 1995 (OBDII...
I'm running Wildfire 4 on Windows 7 now. It works fine. The only issue I've run into is that I had to replace the certified graphics driver with the older 64bit Vista one, due to some terrible 3D performance.
