I was able to replace it in a 300SDL without removing the fan or shroud. I don't think I even took off the belt. IIRC, disconnect the top attachment of the shock, pop the front cover off the tensioning pulley, remove the tensioning pulley (6mm or 8mm hex), position the fan so you can get a 12mm hex on the tensioner bolt. To work within the clearance and what McGuyver items I had on hand, I took a bolt that takes a 12mm socket and jammed a couple of nuts on the shank. I put the tool into the tensioner arm bolt and turned the nuts to loosen/tighten the tensioner arm bolt.

Sixto
93 300SD