So now I have another request and the back of my tach meter asks for a 12v supply but the diagram does not show it. I should say the Tachman revised mine for electronic ignition so I think (duh) I need to get a wire run from ignition.
1972 It is a Pertronic ignition in a regular distributor. I see from the new OEM harness, there is a double pink wire with the female connector on the harness and I can connect it but I'm not sure a. if it for something else and why it is a double wire.
All you need is ignition on 12 volts. The easiest way is to use a fuse tap. https://www.napaonline.com/en/p/NW_785131 Or, you can probe any wire with a multi-meter or test light, and tap into the wire. I would use an additional fuse inline for better protection. The stock tachometer requires NO power, yours does. You don't need a wiring diagram.
Did your car come with a rally clock? If it did the tach plug should already be there factory installed in wiring harness. Hood tach wires were often there taped above fuse box too.
If your car did have the rally clock look for the tach connector. Don’t make it harder than it has to be.