Coolant leak at back of engine.
 

Looking for some help here, this is the situation.

I got home from work and parked my truck then went about the afternoon watering the lawn etc and noticed my truck had a leak that looked like condensate from the a/c. Next thing I know the leak is fairly large and pooling over the driveway and upon closer inspection turns out to be coolant. I then tried to track down where and I came up with this weird hole that looks like it goes into the cab of my truck on the passenger side behind the engine. I took some photos that show where it is pretty well. Any help identifying what this hole is and how I can fix this leak would really be appreciated.

First photo is of the leak on the ground.
Second photo is a closeup of the hole I found it to be coming from. I removed my tire and stuck my head in there to find it.
Third photo is the hole again but farther out.
Last photo is a view of where the second and third photos are taken.

http://s19.postimage.org/tnc5js1db/2..._01_40_508.jpg

http://s19.postimage.org/d0ulap8fj/2..._56_37_280.jpg

http://s19.postimage.org/6bo1uon3j/2..._56_42_773.jpg

http://s19.postimage.org/llnx1vilr/2..._57_00_221.jpg

Thanks in advance!

i cant see the hole , but im wondering if you have a heater core leak and the hole has something to do with a drain for the heater box (to get rid of rain water or condensation).

I circled the hole its coming out of, also if you click the pictures they get larger.

http://s19.postimage.org/h2kv7ufhr/2..._56_37_280.jpg

Is there anyway I could test my heater core to see if it has a problem. From my own research reading about back engine leaks, changing out the heater core seems like a bad time. If its what I must do, I can, just want to make certain before I start tearing apart my dash.

you could bypass the heater core and put no flow thru it ?

How would I go about doing that and if I do that it will not hinder anything other than making it so the heater doesn't work, correct? Won't be too much of a problem as I live in Arizona.

http://www.ehow.com/how_6467976_bypa...2003-f150.html

Is it really as simple as this e-how guide makes it seem to be?