Next step was to add in wiring to connect the isolation unit for the 3rd auxiliary battery in the rear of the truck and the wires to the control box near the drivers seat.

The left picture shows the 3 control wires attached to the left-most isolator-combiner. The right picture shows both batteries in place as I make up the battery negative leads (2GA). Below are 2 shots of the finished installation with expansion tank in place. To its right is the winch cut-off.