68 barracuda tacho wiring help please

hello, cheers for that, did the dash look like mine, where did you run your two wires,cheers nathan.right im getting somwhere, im running a msd 6a so will be using the tach output on that not a wire to - coil, does anyone know if the standard plymouth tacho is voltage or current triggered please? may need a ballast in there somwhere.