Where do the 2 lines that go into the firewall go? One goes to the thermostat housing, I know, but can't find where the other runs to?

 

Seriously? It goes to the pipe that is screwed onto the water pump. Look under the upper radiator hose.

 

That would be the thermostat housing as mentioned in o.p... I have that one... when I got the jeep, the thermostat was capped so there were no lines running to the heater core.... that is the feed line, which I have on. But where does the return go? I am guessing the radiator, but I have nnothing coming from radiator to put on.

 

Ok... I see what happened now... the genius who had it put a bolt into where the pipe for my return goes into so I have to find that pipe so I can get the hose..

 

Rockauto will have it, O'Reilly auto parts can get the pipe too.

 

Also, if you're talking about the 4.0, the water pump has to be removed to thread it in. Depending on the mileage, why not replace the pump while you're at it? Suggestion; replace it with a metal impeller.

 

All done... neighborhood NAPA had the inlet pipe in stock... I cut it right before the bends so I didn't have to take things off and she threaded right in and hooked up the lines, and viola! Heater works... only need it to defrost a couple days a year here in Tampa, but hey... at least I have it! Thanks guys..