"6865864 / ECU 6865866" is ETK part number 6865865 - for cars manufactured from 01.03.2012 onwards.
The ETK part number will usually be +1 of what you see first number on the label.
If your car is 4WD/X-Drive manufactured until 29.02.2012, search for used ETK part 6852825 with label "6852824 / ECU 6852826" or "6862824 / ECU 6852827"
If your car is between 3/11 & 9/11, you can also use the previous part number 6799253, so look for label "6799252 / ECU 6799254" or "6799252 / ECU 6799255"
I just finished retrofit of 5DF on my car and spent days researching this theory...ended well with the right part for my car 🙂
