Need help installing tachometer

deftsound

Please ask me how much my supercharger cost
Apr 6, 2004
945
1
39
Texas City TX
Ok i bought one of those autometer digital pro tachometers for my car. Anyway it doesnt require a module to work.

So it says on the instructions you can connect it to the #1 ignition coil on the negative side. With that being said, how do i know where on the coil to connect it or which side is negative?