My shop manual does outline the removal of the sending unit and connector. To get to it, you have to remove the carpeted panel in the trunk just behind the rear seat. The sending unit is held in place with a large retaining nut.
The manual does state that if the tank is full, to drain at least 8 litres of fuel before removing it.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car