Just picked up my '93 300d after having the evaporator core replaced. I had an independant perform the job (considered doing it myself but wasn't ready to take this one on yet) and although expensive everything is working well.
Just wanted to say thanks to the group here, as I was able to read up on other's experiences and make a decision as to how to proceed. I did replace the vacuum actuators (there are six) that was recommended here, and that cost no extra labor as the shop had easy access to them.
Again, thanks to all for the great dialogue!