Motorcycle Repair: tach instal, sportster, speedometer

Question
I have a 04 sportster. trying to install a aftermarket tach. Directions say to connect in the #3 hole in the speedometer plug. Question is on the plug both 3 slots are empty. what is the color of the wire next to it..#4.plug or do you have a better way.

Answer
since you are installing a aftermarket tach and you are not sure on the #3 hole I am going to refer you to the manufacture. I dont want to tell you wrong and have the tach burn up. Check on the net for the company that made the tach and they should have a help line that you can call.
Good luck and happy riding
Mike