h guys, my nc29 had been stripped of a tacho for some reason, anyhow i sourced a spare from a nc23. ive came to connect it up and there is an additional wiring on the 23 (not just an additional lamp) than the 29? looking through the drawings the 29 has 4 wires, green 12v supply to tacho and lamp? red negative from lamp? and a yellow and green from tacho? the 23 has 3 wires from the tacho unit (yellow/green, green and black/brown. Does anyone know what the additonal wire on the tacho unit is for?

Solid green is the earth/-ve wire for the whole unit.
Brown/white is +ve for the lights inside it.
Black/Brown is +ve for the tacho its self, the 29 doesnt have this.
Yellow/Green is signal wire for the tacho.

You will be able to take the +ve wire (black/brown) from the tacho and tap it into the black/brown wire for the temp gauge.