This will require disabling the Allnames macro (this might just be a variation of the OnSingleClick method, which would make this part unnecessary), a modification of the OnSingleClick methods for each type of mobile (and/or possibly the same function in mobile.cs of the core), and the gump system (both the status gump that you get by clicking and dragging and the portrait gump).
As a quick example, to make enemy mobs "anonymous" to a single click, you would find the method OnSingleClick in basecreature.cs and comment out everything, especially the call
Code:
base.OnSingleClick( from );
since it's what actually produces the name for most clicks. Do the same in playermobile.cs for other players. You'd have to create the method in basevendor.cs since it doesn't already exist. Hmm...
I think there's an easier way to do this, but I'm drawing a blank at the moment...
What is RunUO 1.3e? The current public release is 1.0.0, isn't it?