Voltage limiter, inst panel help

[rp23g7]

I pulled the voltage limiter off the back of the dash to look at it, it is a 3 pronged one, but there is a 4th wire that comes off the panel somewhere below, does anyone know which slot it goes back into, i couldnt see when i pulled it off.

71 Plymouth scamp

 

[69signetv8]

I pulled the voltage limiter off the back of the dash to look at it, it is a 3 pronged one, but there is a 4th wire that comes off the panel somewhere below, does anyone know which slot it goes back into, i couldnt see when i pulled it off.

71 Plymouth scamp

I think...that slips in with the ground prong, and..(if I remember correctly, the ground spade/prong is a tad longer)