[rgunlock]

The new back fits on pretty snug with just the 4 clips. I've stuck the old back on top for one picture in pretty much the original position so you can see that I only lost about 1.5 inches of depth. Then mounted it up. Turns out there was nothing to worry about. The duct work comes up right behind the really shallow area on the driver's side of the glove box. Door shuts nicely.

Unfortunately, I'm going to have to do the glove box mods all over again. I hadn't noticed before, but the "hinge" for the door is just a plastic strip extending down (and part of) the box. It's shot! Going to have to get a new one.