Here are pics of the stainless 1st Gen extender and the black one that's supposedly from an F-150, but fits my '01 ST. At the mounting clips, the black one is slightly narrower, but with a little effort, it will clip onto a 1st Gen. See the 3rd pic. The other side is lined up at the clips. As you can see the vertical supports are further apart on the black one, but they can be easily moved if necessary. The extenders are essentially the same width, and are the same length front to back, but the angles on the side are completely different.
The black one currently has no locking pins in it because I swapped them into the 1st Gen extender, which is the first one I bought and it had none when I bought it. That's the reason I bought the black extender without caring what it fit - I just wanted the locking pins. If we make a deal, I'll put take the pins out of my other 1st Gen extender and put them in the black one. The different extenders use different pins, but they will interchange. I've found the pins aren't all that necessary, so I don't mind having one extender without them as long as I have one with them.
If you continue to insist on using the part # on the sticker to distinguish the different extenders, you're never going to find what you want because the # on the sticker is for the sticker, not the extender, just like the part # on the a/c decal on radiator supports, valve cover decals, etc, is for the decal, not the part it's on. I have these 2 extenders, which are clearly different parts, a second Gen 1 extender, and one from a full-size, wide bed F-150, and they all have the same decal with the same #.
Not sure of the best way to ship one of these. The black one is significantly lighter than the stainless, but the size will make shipping expensive. Disassembly would help, but I don't know how much.