How can I make a Dropdown list that drops the cell location instead of the current text?

My situation is trying to create "Patch" sheet where the output can be selected from a list of 40 inputs. That part is easy with Data Validation but I want the contents of cells that have already picked from the list to update if the input name is changed. IE I select Output cell E2 to be Input 2 from B4 but if I change the input to a different source and rename it, I want the Output Cell E2 to change as well.
The easiest way I can figure out to do this is to have the drop down return not the current cell contents but the cell reference since it would then update. But I can't figure out how to do that.