This is a genuine BMW gasket ring, part number 65 61 1 383 246. The number stamped on the part is 65611383246; BMW's catalog files it under the short number 1383246. You will find it on our Instruments & Electronics shelf, under Radios.
It fits the E36 sedan (318i, 320i, 325i, 328i and M3, 1992–1999), with the M40, M43, M50, M52 or S50 engines — and the European-market versions.
BMW draws it on the Single Parts F Side Panel Teleph.Antenna (65_0231) diagram.
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.