ETK / EPC Parts Catalogue
From E30 Zone Wiki
BMW have a very handy Part Number system, where every component down to the last nut and bolt has a part number to identify it. Making use of this system makes ordering spare parts a lot easier, whether its from an OEM manufacturer or directly from BMW.
There are two main websites that allow you to look through parts diagrams of each BMW model to find the relevant part number. These catalogues are:
Part number cross reference available at: