What do these wires do? Neutral/Safety Switch

[JFetter]

Hello,

My reverse lights have not worked since I bought the truck. (78 K10, auto)
After tracing down the wiring, I found that my neutral safety switch is totally missing. New one on the way...

So I'm pretty sure the light green and dark green connector is for my reverse lights.

Then there are the yellow and purple/white, which have been connected together. This if for the start circuit?

Then that leaves this purple wire all by itself not being used. Does this belong on the neutral safety switch?

Thanks!