Some excerpts from the haynes manual that is euro spec but it helps for US spec cars

Disconnect battery negative terminal

There are two fuel gauge sender units, each one located at the lower front of each half of the fuel tank.

Unbolt and remove the covers from the bottom front of each half yank.

Sender units have drain plugs (tanks must be near empty) and drain any remaining fuel.

Sender unit removal, The retaining rings must now be loosened and removed.
MB techs use a special tool which engages the holes in the ring, possible to fabricate a home-made version.

Removal tips: recover special shaped gaskets, Note the location of stud and grove to ensure correct refitting. When removing left hand sender unit, disconnect the internal pipes leading to each half of tank.