Thx for replies. No - that is not the battery cut off switch. I have that switch and that is on the front of the battery box. This pic is of the posts on the side of the battery box near the shifters. These posts are marked with polarity (+ or -) while the battery cut-off switch just toggles the ground wire only.
My FSM shows this to be "split charge terminals" and says its for 110s only. I am trying to figure out what that is. The box behind the coil in the engine bay terminates both the brown and the white-brown wires and I am not sure what that does either. Its literally a block box with Lucas on it, two small wires go into it and the two large battery cables come out the bottom.
'93 NAS D110 #437