This is a genuine BMW moulded part column A left, part number 41 21 8 238 505. The number stamped on the part is 41218238505; BMW's catalog files it under the short number 8238505. You will find it on our Exterior Body shelf, under Other Bodywork parts.
It fits the E46 coupe (323i, 325i, 328i, 330i and M3, 2000–2006), with the M52, M54, M56 or S54 engines — and the European-market versions.
BMW draws it on the Cavity shielding, side frame (41_1263) diagram. 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.