The plug with the #2 on it is an EZL trimmer plug (#274 in the attached diagram). Here's a lengthy discussion on that subject alone.
EZL Trimming Plug Guide
If you want to try a used one, check ebay.
It looks like there is a split in part numbers. Up to the end of 1992, it is 013 545 6332. Starting in 1993 it is 014 545 4532. See the attached parts list from the Mercedes epc.
I don't know if your engine wiring harness has been replaced yet, but a bad harness can destroy this module.