Where I circled in red is where I grounded the cable. You can ground it anywhere I felt this made all my cable ends in one place and easy to access after. This this where the big round bar behind the dash is.
This is the center harness of the 3 behind the cluster. The one I have circled is B4 which is for the rear diff sensor. The one above my finger is for IC Spray light.
I also picked up the Stay Earth and attached it to the rear diff. This bracket goes to one of the bolts holding the cover on the rear diff. I then attached both cables. (Sensor and ground)
Everything is down. When you turn the key to On(no engine). You will see the rear diff temp light on.
When engine is turned on the light goes off.
Thats all it is. Hopefully this will be useful to somebody.