WARNING: This page is about a different car, the 2010 BMW 135i, 2009 BMW 135i, and 2008 BMW 135i. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Measuring Ring (23 1 070)
Courtesy of BMW OF NORTH AMERICA, INC.
NOTE:
For determining shim ring between outer bearing race and circlip of countershaft