I'll look at the blower motor this weekend, see if I can get a better idea what this stuff is. I know a bad heater core is most likely the source, due to the nature of the problem. But I honestly believe that's oil, not coolant. Before we changed the oil, when I first notice the leak...or run off, or what ever you want to call it...the fluid was black, like dirty oil, now light like clean oil. IDK, maybe that's just a coincidence. So, assuming it's a leak with the heater core, if I turn of the heater/defroster next time we drive the truck, will the leak stop? Or is it going to leak all the time, regardless of if the heat is on or off? Just looking for a way to try to confirm it's leaking heater core, before we go off and tackle that repair/replacement job.

EDIT: I'm trying to avoid spending another day tearing apart the truck and putting it back together, trying to fix something that seems wasn't the issue? ( aforementioned plenum gasket repair ) :EDIT

 

So, it's deffinately a heater core leak. Took the truck for a short drive tonight, and got a good ammount of fresh run off. And for starters, I tried the whole taste thing, and whoever said antifreeze is kind sweet, is LIEING like a dog in summer underneath a shade tree. LoL! That was the nastiest thing I think I've ever tasted...but after driving the truck, the new run off was not black or brown like before. It was clearly green. Thanks everyone, for all the info.

 

If I had told you it tasted terrible, would you have tasted it?

Heater core is a fun job. Dash needs to come out.