What is the application you want to use it for? Most earlier cars used a 12mm pilot bearing... according to realoem it looks like the changeover happened late 1990-ish.
From what I can tell it looks like the 260s all used the 12mm bearing.
Edit: Part numbers are 11211720310 for the 15mm bearing and 11211709681 for the 12mm.
Last edited by Duct_Taper; 05-12-2009 at 10:21 PM.