I have a drip under the truck, 86 F250 diesel, passenger side, mid to rear engine. The drip is not diesel. It is not oil. I doubt it is antifreeze. It appears to be just water.

The AC doesn't work on the truck, but I took the AC belt off any ways just to make sure it wasn't the AC condenser wasn't working and/or creating water run-off.

The leak appears shortly after the truck has been parked. It is not dripping when I stop. I'm sorta baffled as to what it can be. Any suggestions?

 

Water dripping from your exhaust.

 

Water can get trapped in cavities and pockets within the truck during a rain.
After the rain some of this water can escape if the truck is parked on a different angle.

I'm just guessing... I have no idea without seeing it and especially since your Air Conditioning doesn't work any more

 

i put a bucket under the drip, then next morning i looked and the water had a greenish tint, crap. so it is anti-freeze.

looking further, with a flashlight, i found that the engine block heater has a slow leak and get bigger when engine is hot

 

NICE !!! Cheap inexpensive fix. Could quite possible NOT cost anything to fix.
Remove block heater. Clean BH and clean opening and reinstall.