This is a genuine BMW torx bolt, part number 24 20 1 423 383. The number stamped on the part is 24201423383; BMW's catalog files it under the short number 1423383. You will find it on our Transmission shelf, under Control unit EGS.
It fits every E46 body style (320i, 323i, 325i, 328i and 330i, 1999–2006), with the M52, M54 or M56 engines — and the European-market versions.
BMW draws it on the A5S325Z lubrication system (24_0889) diagram. BMW's catalog calls for nine of these at each place it is fitted. It weighs about 20 g (under 0.1 lb).
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.