I have a coolant leak where the upper transmission line enters the radiator. There's a large nut looking item there and it appears to be between it and the radiator.
Assuming your radiator is more than 5 years old, it is replacement time. It makes no economic sense to put off this repair because an ultimate failure will strand you and create more cost than to have it repaired while you can yet drive it to the shop. An ultimate failure while driving at highway speed can damage the engine.