This is a genuine BMW supporting rail, part number 51 71 7 056 337. The number stamped on the part is 51717056337; BMW's catalog files it under the short number 7056337. You will find it on our Interior Body shelf, under Other Body equipment parts. It supersedes the older number 8243226, so a part carrying that number is the same part.
It fits the E46 convertible (323i, 325i, 330i and M3, 2000–2006), with the M52, M54 or S54 engines — and the European-market versions.
BMW draws it on 2 diagrams, among them Battery tray (51_3277) and Battery holder and mounting parts (61_1424). 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.
