I found some Oxygen Sensors laying arond the house from when I did my headers.
My car had 150 000km when this were taken out.
They are Pre-Cat O2 Sensors.
Before Catalyst : Regulating Lambda Probe : 320mm
Part # 11781742050
Here is the cross reference http://www.realoem.com/bmw/partxref....2050&showus=on
$70 OBO each.