Electrical: Where does the tach wire pass through the firewall?

[studefan]

I have a tach in my 64 HT. There is a long black wire on the tach wiring harness under the dash. This wire passes through the firewall somewhere.

Two questions please. 1) what firewall hole does it pass through? and 2) where do I hook it up on the engine side?

Thanks much.

[StudeRich]

The only place it can connect, is the Coil (-) Negative Side, Terminal.