If you can sell this on e-bay, you will have proven that someone somewhere will buy anything, as that plunger has zero practical value. You can't replace plungers. They are (at least Bosch, Porsche, and John Walker assert, which ought to be authority enough) matched during manufacturer to the particular assembly.

Still, pretty bizzare thing to find.

Walt Fricke

What a quandry. What if the one in the FD is the "replacement" because the prior owner at some point "lost" the correct one? So, this car will always have issues running because it has the wrong plunger? How to know which one is right?!

Well, the car did run fine, so I guess that's evidence enough that the "correct" plunger is in there.