Re: Auxiliary air pump # 0-580-000-021
If you want to buy a spare part you should use the Mercedes or if you have to, the Chrysler part numbers.
You were using the Bosch part number and many of these ads skip that number and use the auto manufacturers number.
As you have found out that though they may look the same they are in fact quite different.
You ordered one part and it had a different part number altogether.
Bosch#0 580 000 011 (MB #A 000 140 37 85) instead of Bosch#0 580 000 021 (MB# A 000 140 43 85).