That clears up quite a bit. I'll be sure to make a note of that on my W124 site.
Anyways here are the partnumbers I pulled from my car for the mysterious big boxes
0 280 800 216, this one says jettronic so that was self-expl.
0 265 101 016, the box behind it...
004 545 46 32, wondering what it is called..
I would test that "aux.fan" relay which Steve thinks is the fuel pump relay under the seat.
Wish I had full schematics for these cars - when is payday?