Ok, so update... looks like there is a 3/4 (at this point I'm guessing size, may be 1") hose that goes to the back of the engine... looks like a return for cooling from the head maybe? Just have to find out where the other end connects!
Ok, on my 2013 Sahara unlimited I have two stainless lines going to the heater core connections at the firewall. One has another hose connection welded to the side of what I believe is the return line to water pump. Anyone know where that connects to??