Someone correct me if I am mistaken, but 88 300E were not the models which were so likely to have cracked insulation in the engine compartment wiring. I thought that was mid 90's 300's and 320's. Doing a search on wiring harness problems will shed light on that question.

What problems are you having? If nothing is wrong it would not be cost effective on that old a MB to do it just for looks. Some hack mechanics might have opened the outer jacket to take readings, but if it has been closed up and taped you should be OK.

I think these may be the reasons no one has jumped in to help you... Tell us what difficulty you are having which might relate to the wire harness?

Good luck to you,
DanielW