Coolant leaking from rear passenger side

Good morning all - I tackled the big job of replacing the very rotted original upper and lower trailing arms and rear shocks on my 1998 Expedition (5.4L EB) yesterday with a friend. It sits in a much better position and the rear end now feels much firmer, not to mention safer.

That said, I now seem to have exposed a coolant leak coming from a very odd position. Coincidentally it is coming down at the front bolt of the lower trailing arm on the passenger side of the frame. By the time I noticed the leak on the pavement underneath, I no longer had the rear end up in the air on stands so I was unable to get a better look at it. I am traveling out of town for the next few days so will get a better look at it when I return, but wanted to know if anyone else might know the source of this mysterious coolant leak. It's definitely coolant too. Green and sweet smelling. There is no moisture up top in the engine bay at the normal spots like the upper/lower radiator hoses or thermostat housing.

I searched on the forum last night and saw a few interesting posts about it being the rear heater core, but if I understand correctly that is on the driver side rear and I have no puddling in the rear inside of the vehicle or under the driver side rear.

Feed or return line for the rear heater core would be a thing to check. If you are lucky it is just the core and the coolant is traveling down a line.

stamp11127 - I'm partially encouraged by your response. I will hope that it is a feed or return line to/from the rear heater core until I get home to inspect it more closely. Does anyone have a diagram of where these lines run? I am not terribly familiar with the use of a rear heater core as this is my first truck. I'm just looking for a starting point to finding the source of the leak. Any help in understanding where these lines and the types of connections they are is very appreciated.

Those lines run down the passenge side also they may have a foam cover on them. Ther are 4 lines running under the floor 2 are for heat and 2 are for a/c. They cross over to the drivers side just about at the rear wheel.

Thanks 05expedeb! I will take a peek underneath the floor when I return. I'm guessing with the proper illumination I should be able to find the lines and track the source of the leak. I'm hoping that a connection on one of the lines has just come loose. I'm told that replacing the rear heater core is not difficult, but time consuming to get to.

FWIW - While 2500 miles from home in Utah, I had the heater code bypassed so as to stop the heater core from leaking any further. It caused the cylinder 4 COP to go out and was leaking enough coolant that I was sick of having to top off the system every few days. Not to mention the mess. I now have the pleasure of digging into the dash to replace the front heater core now that the Expy is back home in Northern Virginia.