2001 ford f- 350 with the 7.3 diesel Leaks antifreeze coolant?

I just put in a brand new ford oem radiator
There's an aftermarket coolant reservoir
It still leaks from the top by the radiator / reservoir
Any one know what this could be?

This is a closed system. A small tube under the radiator cap has a hose attached to it that goes to the reservoir. When the coolant expands (gets hot) it flows thru this tube into the expansion reservoir. Either the tube in the neck of the radiator is leaking or the hose is. If it's the radiator you should have a warrantee. Otherwise just replace the hose. Your post is unclear but the leak could be at the expansion tank which is plastic, inexpensive and should be replaced.

There's a metal tube behind the second alternator on my 2001 f350 that is dripping anti freeze. What is this tube attatched to that could leak