Today, I was planning to repair or replace the fuel sending unit on my 300D. A post I found on another site said to remove the back seat.
So I did, guess what, not there. However, a little poking around and I found it. All you need to do is remove the first aid kit storage box and there it is!
You need a VERY LARGE socket, 44MM? or, remove the wall inside the trunk, behind the seats(easy,4 screws)and use a pair of channel locks.
Mine turned out needing to replaced. Reading this forum gives me the confidence to really try DIY stuff.
84 300SD (sold)
P.S. If anyone needs advice regarding furniture, I'm sort of the "Benzmac" of that arena.