Part number for final drive magnetic drain plug is...
331 177 705 854 Magnetic Drain Plug Final Drive, K4X and K2X Price $9.70
Bought from BMW of Santa Cruz County.
This plug has a darker gray color than the silver one that matches the final drive housing which makes it easy to spot.. The magnet is deep inside it and peened into position. Has a strong pull so it should fill up that little cavity pretty well if it starts doing what it's supposed to do.
I don't believe this was on the '06 models and just began appearing on the '07 ones.
Didn't come with an O-ring. Luckily, I had one.