Thanks for reply. I have the full Mopar shop manual for this car and wiring diagram shows 4 wires from the tach exactly like mine. Black to ground (tested fine), Orange to light- works, Dark green to positive side of coil - done and tested for contact, Violet goes to a Violet with white tracer line on console wiring - it is the 12V power and is working.

You say the wire should be on the negative side of the coil not the positive?????

This may be a dumb question but how does the tach pick up an ignition pulse on the positive side of the coil. I thought it had to read this from the points. As you say, the points are connected to the negative side so maybe the factory wiring diagram is wrong.

This is a factory correct tach, purchased from a fellow who dismantled the same car and he said it was working. I am restoring this car and adding as a factory option so was wiring it as per the shop manual.