Curiosity got the best of me -- I bought another crank sensor off eBay, but this time a true-blue Mopar/MB part ($20 including shipping). Just installed it, and it took less than ten minutes since I knew what I was doing this time, and the connector came off much more easily.

Comparing the parts, the new Mopar replacement has MB markings, but is slightly different from the original MB sensor. And, interestingly, the new Mopar part is exactly the same as the other new one I got off eBay, except the part numbers had been melted off it (so that the part could be wholesaled under a different brand, with no MB warranty). Seen this before, years ago, for another electronic part found via NAPA for another Mopar.