I installed Stillen sways and I think I had a similar part. My car is an 04 euro spec 350z. I got no idea what that part does, but I just took it out and putted it back it. I haven't had any problems.

 

Looks like a Hella logo on the part. Possibly a rotory angle sensor, like some have mentioned, since the plastic connection really isn't strong enough to provide a force only transfer motion.

http://www.hella.com/hella-com-en/as...r_GB_TT_09.pdf

 

Well, I currently have access to over 1000 collective years of automotive tech. I'll ask some of the professors maybe one of them will have an idea.

 

Most interesting thread on my350z in a while.

lol, what is this thing?

 

I never actually looked when I was under my car all last weekend to see if I had it. If I do bring my car in the shop today I'll get it on the lifts and check. I know it's UKDM..HAHA, but maybe SOME here have it also.

 

Ok finally figured out what it is.

Some points to cellude, it is a rotory angle sensor for the head lights so when you go over speed bumps it adjusts the head light angle so you do not blind any on coming traffic.