yes factory. actually the aftermarket ones wire did match up. problem was that there was not a coded key for the aftermarket one, so any dess would work. the oem ones wires are all plugged in according to color but i have a solid grey left over and i assume its not used but i just want to confirm.
Looking at the wiring diagram, it looks like the grey wire should be grounded, but the drawing I’m looking at isn’t real clear, so I’m not 100% positive on that...
I concur....grey wire goes to tachometer (for rpms). On my '96 GTX it also branches off to the main "infocenter" guage (which also reports rpms if you scroll through the menu (if you don't have a tachometer)).