Remove the flange. If necessary, use puller 116 589 193 300.
Loosen the rear cover mounting bolts (see fig. 178).
Fig. 178. Removing the rear cover of the gearbox.
Remove the back cover.
Using a 52 mm diameter mandrel, press out the oil seal.
Press a new seal into the cover.
To facilitate installation, glue a new gasket to the detachable surface with grease.
Install the reverse gear shaft with the flat side facing up.
Place the rear cover on the driven shaft.
Slide the cover onto the mounting bushings.
Tighten the mounting bolts evenly in a crosswise pattern.
Lubricate the working edges of the seal and the working surface of the flange and place the flange on the driven shaft of the gearbox.
Tighten the new self-locking nut by hand and then tighten it with a socket wrench.
Fig. 179. Rear cover of the gearbox with gasket.
1 - gasket,
2 - oil seal,
3 - cover.
Fig. 182. Rear cover of the gearbox.
1 - tachometer pulse sensor,
2 - pulse sensor housing,
3 - cork,
4 - sealing ring,
5 - oil filler plug,
6 - hairpin,
7 - gearbox housing,
8 - gasket,
9 - rear cover of the gearbox,
10 - oil seal,
11 - bolt,
12 - bolt,
13 - bolt,
14 - hairpin,
15 - rear cover of the gearbox (mechanical tachometer drive),
16 - tachometer drive gear,
17 - drive gear shaft,
18 - oil seal.
[Original source of information mercedesman]