Reverse lights under dash Wire routing 65 Belv

[1965belvedere2]

While I was playing with my turn signal switch wiring, I noticed that my Column mounted reverse light switch did not have the connector attached. I found it and plugged it in. But the lights did not come on when I put it in reverse. So I found the power wire also hanging under the dash, I jumped it with 12v power, put the column in reverse and VIOLA' the reverse lights came on. Looking underneath the dash I cannot find where this wire plugs into. Its a factory plastic covered female spade connector. I looked on the Light switch for an "accessory" spade to plug this wire into and theres nothing there. And I dont see any nearby loose wires where this plugs into. Does anyone know where it plugs into?
See pics