Genuine BMW part 26 12 1 229 540: Compensating plate. The number stamped on the part is 26121229540; BMW's catalog files it under the short number 1229540. You will find it on our Drivetrain & Axle shelf, under Other Drive Shaft parts.
It fits the E46 sedan, touring and compact (325xi and 330xi, 2001–2005), with the M54 engine — and the European-market versions.
BMW draws it on 2 diagrams, among them Drive shaft, single components, 4-wheel (26_0182) and Drive Shaft-Cent.Bearing-Universal Joint (26_0194). It weighs about 10 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.