Very helpful read thanks guys.
I am in the same situation, i have found the loop wire, but cant find the other 2 wires.
I have found 2 attached to a sounder? is this what i am after, or other wires somewhere else.
Also, i dont have a switch, so was looking at these, will any of them work?
https://jdm-car-parts.com/collections/electric-components-nissan-datsun-fairlady-z-240z-260z-280z-280zx/products/hazard-switch-for-1969-1971-1-2-datsun-240z
https://jdm-car-parts.com/collections/electric-components-nissan-datsun-fairlady-z-240z-260z-280z-280zx/products/hazard-switch-for-1971-1-2-to-1972-datsun-240z
https://jdm-car-parts.com/collections/electric-components-nissan-datsun-fairlady-z-240z-260z-280z-280zx/products/hazard-switch-nos-for-datsun-240z-series-2
Thanks all!