at one end of the harness is a big square plug. somewhere near that plug is a white tag which has part number and year of manufacture information. if the date is recent then you have a new harness. if the date of manufacture is '93 - '95 it is probably original or, if it was replaced, is suspect again.
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"