Bosch/BMW ECUs, specifically their Motronic line, have a hardware part number beginning with “0 26(0/1)” and ending with 6 digits. The final three digits of that number are commonly referred to as the “ECU Number” or “DME Number”. These last three digits are the numbers you will use to identify which ECU you are running.

Below, the hardware ID and colloquial “ECU/DME Number” are outlined.

Some examples are:

BMW E30/34 325i/525i “173” ECU
BMW E30 318i “175” ECU
BMW E30/34 325i/525i “524” ECU
BMW E30/34 325i/525i “525” ECU
BMW E34/36 M50/S50 “413” ECU
An alternative ID sticker for the “179” ECU

Further information on identification (1890-1991): http://www.sssquid.com/v3/wp-content/uploads/2018/01/DME_id.pdf