A mechanical question about...

...2000 Chrysler Grand Voyager with a 3.0L 6 cylinder engine. Too late, I already own it.

I ran by work today and when I parked I popped the hood to check the transmission fluid. I looked down to the asphalt and saw a steady stream of green anti freeze flowing downhill from under my van. I turned the engine off and took care of my business. I got back out saw that I had fluid in the overflow reservoir. I decided to try for home and made it. The temperature gage was maxed out as I neared the house so I turned off the motor and coated in. So I let it cool down, checked my Haynes manual, spoke to a mechanic friend and my father in law. FIL thought it was a freeze plug gone bad. Friend said either heater coil or water pump. Once cool I looked inside the radiator and it was dry. Hoses were fine. Floor in front of passenger seat was damp. Looking under the car told me nothing but fluid had splashed everywhere. So I topped of the radiator. Put two quarts of oil and a bit of transmission fluid in it. The oil was not milky. Then I cranked it up. Temperature gage went to center and stayed. Looked under the car. No fluid pouring out. Hoses ok. Radiator looked ok. I drove it around the block and checked it again. No pouring fluid.. Drove to my mechanic and was told it could be a number of things .They need to stress test it and was told to bring it back in the morning.

If there are any gun loving mechanics out there who might have an idea please share.

UPDATE: cracked radiator