Cluster Plug Pinout Diagrams - 1986 Pin #6 mapping?

[blindbug]

I found the below pin-out diagrams for the cluster plug on my 1986 Non-Gauge C10. When I look at the utilized pins on my plug, however, I see that there is (1) additional pin that is utilized on my plug that is not mapped in this diagram.

For me, I have a Pin #6 in my plug, but in the diagram I don't see #6 as being utilized in 1986.

Does anyone have any idea what pin #6 is mapped to? Does anyone know if the attached diagram is accurate for 1986 non-gauge (idiot light) cluster implementations?

Thanks in advance.