Jim, thank you so much for the info. I was looking at some youtube videos, and one guy used oven cleaner to remove the worst of the black sludge, it looked real good. When I get ready, would you be willing to rent the tools for me to do the job? I am sure that whatever car I get, it will have some amount of black death that will have to be dealt with. I am excited about the chance to finally enjoy the experience of owning and driving one of these cars. I thought I could not get much better than the '99 E300 W210 I had for a few years (my friend loves it and drives it every day), but the consensus is that there is a measurable difference between those two, let alone the CDI vs a W123. I am surprised that the CDI is not on the list of the top 10 best Mercedes-Benz automobiles:
Top 10 Greatest Mercedes Ever Built
My search continues, and will not be done until I have just the right car in my garage. Lord willing, that time will be soon!