This is a genuine BMW set of fittings f side window, part number 51 37 7 020 619. The number stamped on the part is 51377020619; BMW's catalog files it under the short number 7020619. You will find it on our Interior Body shelf, under Other Body equipment parts. It supersedes the older numbers 8253887, 8253888, 8253889, 8253890 and 2 others, so a part carrying any of them is the same part.
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 Door Window Lifting Mechanism Rear (51_3687) diagram. It weighs about 22 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.
