tachometer wiring help 1967 GTX

[Pops1967GTX]

Just got my hands on 1966 console tachometer & sending unit.It has three wires. I read somewhere that 1967 verison had 4 wires & no sending unit. need help wiring..... thanks

 

[SwedCharger67]

The 67 Charger does not have a sending unit for the tach, while the 66 has. In your case my guess is that you have the following 3 wires:
1. +12V feed
2. the negative side of the ignition coil
3. the instrument light
The case is grounded via the console
Good luck, Martin