Water pump

Depends on where it is coming from. It may be as simple as a hole in a hose or a loose fitting but those will create a slower leak than you are describing. Stick your head under the engine and determine the source. The water pump is typically located on the front of the engine block and can be externally inspected for your leak.

Could it b a freeze plug? I don't BELIVE that it's a connection or hose... Do u know about how much a water pump gernelly runs? Also about a week ago the transmission line at the radiator blow off.. Wud a sticking thermo have anything to do with that? I can't figure out wats going on with this truck but when the trany line blew and was replace and refilled with fuild now I don't have 3 and if jumped into overdrive U can feel its in gear pushin U but the rpm are high, like it's in a bind, never had any trouble out if the trans til that day..Help help! Going crazy with this thing! Lol

Could be a freeze plug but these are separate issues. The engine coolant and transmission fluid are separate and the trans cooler is not associated with the coolant radiator or thermostat. Are you certain that the trans was filled completely when you fixed the fluid line? As for the coolant leak, you will still need to crawl under and look. Good luck.