Gee, that third link you provided wasn't very helpful... didn't even seem BMW-related. [image: ;)]
I think got my answer from Penske Parts and this is the breakdown of what I found:
#11517546994 - No longer available since 2007-02, superceded by 11517563183
#11517563183 - No longer available since 2008-04, superceded by 11517586925
#11517586925 - Currently available
My belief would be that if Penske Parts couldn't sell it to you, I would hope that BMW stopped using those part numbers in manufacturing by the dates they were no longer available, if not sooner.
Thanks for the links!