74 Charger SE: Cut off black speed control wire?

[74ChargerSE440]

I found another black cut off wire (I wonder for what reason anyone would cut off this wire) underneath my dash that should be plugged into the accessory feed.
- What is the color of the missing bullet plug?
- This goes into the yellow connector somewhere under the dash?

 

[Nacho-RT74]

This is a pre 72 setup (diff lever at steering column) but pretty much the same harness for all those years

 

[Nacho-RT74]

Another pic