Coolant leak over transmission

I have a '95 Aurora with 135,000 miles. A few days ago, after driving for about 25 minutes, I noticed the smell of coolant while at the stop light and a little steam from under the hood. I stopped and could see nothing from top side except for some steam coming from the firewall area. Looking under the car I found the engine pouring coolant from the back side of the engine. This lasted for about a minute and slowly stopped. When I drove the car home about 10 minutes after it was started the same thing happened. When the leaking stopped I drove the car home (a 30 mile trip) with no more problems. I got it home, up on stands and nothing, not a drop. I left it there and the next morning I cranked it up and all was fine for about 20 minutes and the leak started again. I mean this a good leak. She lost about a quart of coolant in a steady stream, then as before it just stopped. I left the car running for another 5 minutes, took her off the stands, drove around for about another 30 minutes and nothing. While it was leaking I couldn't see where the fluid was coming from, only that it is pouring onto the transmission making it appear the coolant is coming from the front transmission pan. I couldn't see around the transmission to find it nor could I see anything leaking from the top side. The radiator and the water pump were replaced couple of years and I checked them just for the heck of it and they are good, no leaks. I checked the one hose which passes on the driver's side and ties back into the engine and could not find a leak on it either. Does anyone have any ideas as to what the problem is and do I have to pull the engine to fix it? Thanks, Desertmage

Kind of sounds like it may be coming from the heater core or one of the heater core hoses.