What is the aluminum 2 inch tube behind the water pump bracket Runs into block

Sounds like the by-pass tube. Should be a hose from the water pump to that tube if I remember correctly.

The one toward the rear, center of the pump is what the 'rubber' bypass hose hooks to. The hose is most likely where your leak is. The ac compressor needs to be moved out of the way to replace it. Or to even see it actually!! The other longer but smaller tube that is on the drivers side of the pump, feeds one of the heater hoses. It has an o-ring seal at the pump and has a bracket that is fastened under one of the front 'timing' cover mounting bolts. Common for leaks at either place after water pump replacement also!!!

rec repl water pump at the same time