Man these engines are a last of an Era. The video was helpful too and it's a clear miss, I appreciate you uploading it.
Speaking of engine longevity, there are people on bobistheoilguy who go to great lengths to reduce engine wear as much as possible with bypass filters, pre oilers, and top of the line synthetic oils.
Sometimes I feel like doing the same but that'll have to wait.
Also I noticed sometimes E300's have different seats , your's are the one's with the old style vertical stitching similar to what was offered to all W124 Diesels, and yet mine is older with the newer style seats. Weird.
Did Mercedes offer some sort of interior package back in the day? Case in point.
Old style
https://raleigh.craigslist.org/cto/d/1999-mercedes-e300-turbodiesel/6766739274.html
New style
https://richmond.craigslist.org/cto/d/1999-mercedes-benz-e300-dt/6767660298.html