This is a genuine BMW hex nut, part number 51 71 8 172 850. The number stamped on the part is 51718172850; BMW's catalog files it under the short number 8172850. You will find it on our Interior Body shelf, under Other Body equipment parts.
It fits the E36 convertible (318i, 323i, 325i, 328i and M3, 1994–1999), with the M42, M43, M44, M50, M52 or S50 and other engines — and the European-market versions.
BMW draws it on the Single Parts F Vibration Absorber (61_0096) diagram. It weighs about 39 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.
