Cover cap, alternator — a genuine BMW part, number 12 31 7 788 820. The number stamped on the part is 12317788820; BMW's catalog files it under the short number 7788820. You will find it on our Electrical shelf, under Alternator with motor and mounting.
It fits every E46 body style (318d, 318td, 320d, 320td and 330d, 2001–2005), with the M47N or M57N engines.
BMW draws it on 2 diagrams, among them ALTERNATOR PARTS 120A/150A Valeo (12_0914) and Generator, individual parts (12_1199). It weighs about 40 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.
