ignition control unit
 

I recently changed the ICU on my 1991 300E and noticed the mechanic replaced my old unit with one that had Orange lettering A75249 on the upper right hand corner. Of course it also has the MB emblem and part number on it. I was wondering what this orange lettering meant and if this meant that it is a refurbished unit. Anyone's help would be greatly appreciated.

It may be a used unit. We mark our EZL (ignition modules) with a paint marker to determine if they are ours or not. Sound like a warranty issue that you should take p w/ the shop.