I have an '88 260e and a '92 300e 2.6 (like yours). Both cars have the spash pans still intact but for some reason MBZ did not make the oil drain plug accessible on the '92 design. Every time I change the oil in the car I have to take the splash pan off. I suspect this is why a lot of cars are missing the pans. I also suspect this is why a lot of owners are topsiding their oil changes.

My '88 model has a little cutout in the pan to access the oil drain plug and I wish the '92 had the same.

John