That's a transmission cooler line. There should be 2 of them. One is the supply, and the other is the return.
There are several different ways that can be attached. Some simply screw in, and others are a special connector. I believe this vehicle will have the screw-in type.
Since it's leaking, it could be loose or even have a small pinhole in the steel line. I attached a pic below showing what I believe you will find if you continue following the hose to the cooler. Also, I believe the cooler is not part of the radiator but a separate cooler in front of the radiator.
Let me know if that is what you have.
Saturday, April 23rd, 2022 AT 8:17 PM