The radiator has only had an antifreeze mix in it, a gallon of antifreeze was the 1st liquid poured into the new radiator. This motor has not been run long enough to reach operating temp yet, doesn't that kind of make the water contamination from the radiator pretty unusual?

I'm really thinking the water came from the trans sitting. Since the motor/trans has been in my possession, there has been a drive shaft yoke in the tail stock, the converter has been in place, and cooler lines with an old trans cooler (that has hung on my shop wall for nearly 10 years) hanging on the end of the lines, and a dipstick in the fill tube. When it was put into the truck, the motor/trans was covered with a tarp, but the truck spent the winter outdoors.
When the motor/trans came here, everything was open and the trans sat on the floor of an unheated garage for about a year with the torque converter out of it. As I think about it, most of the atf in the trans now was in it when I got the it. The fluid was clean and had good color.

I will be having the system flushed, but now my concern is about the source of the water, we are all in agreement the contamination is water, right? Gene