Aerial diplexer — a genuine BMW part, number 84 51 8 360 972. The number stamped on the part is 84518360972; BMW's catalog files it under the short number 8360972. You will find it on our Instruments & Electronics shelf, under Other Communication systems parts.
It fits the E36 convertible (318i, 323i, 325i, 328i and M3, 1994–1999), with the M43, M50, M52 or S50 engines — and the European-market versions.
BMW draws it on 2 diagrams, among them Side wall aerial retrofit kit (03_3103) and Single Parts F Side Panel Teleph.Antenna (65_0249). It weighs about 300 g (0.7 lb).
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.