[Erich]

 http://members.aol.com/Turbo745i/OBC1.html

OBC II
 http://www.geocities.com/ebaines/e28_obc.htm

Laut U.K. Forum:
For UK cars, OBC 1 is fitted to cars up to around the 83/84 A registration. OBC 2 fitted from the B registration, ie '85 model year.