interesting hook-up

[livelong]

OK, so maybe i misstated a bit, but anyways, heres the question:

I want to install a tachometer on my 95 corolla (actually a geo prizm...but lets not get technical) so im going to go to a junk yard and grab a whole new guage panel/cluster, spedomemeter, gas, temp etc. and install it.

Before I do this, Im looking for help as to how to know weather or not my car already has the hook-ups. I checked for thr requisite green wire on the ignition coil, and it appears to go to the speedometer cluster. But is there something tell tale i can check for, b/c right now, after I have removed the instrumentation panel, I can't just look and say, 'oh, there's the hook up!'.
Would it normally be the case that if the car DOESN'T come with a tach, that the hook-up to the coil would have to be done?? Or is it possible that the leads already in place on some makes/models??

Help here appreciated. Thanks.

Omar

[drdisque]

most OBD2 cars come prewired for any gauge cluster to save cost and because the ECU needs that information to run. your car is OBD1 though so I'm not sure.

[livelong]

hmmm......

inconclusive, but thanks for help.

Omar