Nothing unusual. There are some tabs for lining things up and the cap should fit on one way only. As always, remember where the number one cylinder connects and the direction the firing order goes on the cap.
When you get the rotor out there is a dark grey cover, also fits on one way, and under that is an area, kind of a pocket, that on my car's distributor is where oil, apparently from the engine that lubes the distributor drive gears and bearings collects. I usually clean it out whenever I take the cap off, which is not frequently, and find a small puddle in the drain pocket. I believe the grey plastic cover is a shield to keep oil from flinging up into space where the spark is being distributed. Make sure you get the grey cover back on correctly - which is not difficult as if you pay attention, it has a tab that fits into a cutout one way.
Good luck, Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)