Okay, from what I've gathered:
1) On the ETK you can not even select the part on my car...It says part is not installed on vehicle. '00 323Ci.
2) However, the part is selectible for cars produced PRIOR to 9/99. So I'm not certain it exist on those car unless I get an opportunity to get underneath one.
3) Several posters here have suggested that it DOES exist on Xis.
That leads me to believe that it does exist on pre 9/99 cars and Xi's only.
Those living in L.A...I would love an opportunity to poll our cars, get it up on jacks and look to see what models have it installed and what doesn't. If you're interested, drop me an email.