If you have a set of parts catalogs, look at the illustration for the 65-66 Custom cab ( fancy). It shows it behind the area of the back of the cluster. Look for the 10804 basic and the 18A952 is there, but is very small. It has 2 flat bladed connectors, one male and one female, on it. You won't find a better drawing or pic of it anywhere ion the books, unless you actually take a actual pic of one.

Barry