[Chevelle-List] Need help -- which wire for tach???

[Galen and Melissa Love]

I need a little help...  For the factory SS tach in a '70-72 Chevelle, I need to know what wire should is used as the tach signal wire in the engine harness.  If anybody knows, please tell me what color the wire is, what it connects to (coil positive?), and where it is in the connector on the firewall.  I have a'71 wiring diagram, but after looking at it, I'm still not sure.  It doesn't go into the detail I'm looking for. Thanks for the help, Galen