My only addition to this, while it is very well-done, would be to add another more "correct" way to make the skirts fit. I removed the entire spot-welded in panel that the ES has. When you remove that, the metal that all 3000gts have and the metal that the skirts are from the factory meant to mount to is exposed and accessible. Basically, the ES's already have the EXACT correct mounting points for the skirts to fit w/ no modification, they're just under that stupid panel

. These pictures might help to explain what I'm talking about.
Also, I have a picture showing the section of metal to remove so that the 1st-gen 3000gt front turn signals fit, here:
Lastly, this picture shows the location of the original backup lights wires, as well as where the wires for the new backup lights are in the center garnish. Not everyone realizes the ES cars had the wiring for center-garnish backup lights from the factory, but they do. The wires are taped up inside the trunk, behind the plastic panel, directly behind the two holes identified in red. So here they are:
Nice job either way! I just wanted to add my own info too. This needs stickied.