Bernd,
yes you have to remove the gearbox mtg rubber and the gearbox mtg bracket from under the car,it is easier if the car is on a hoist.
You can do it on the floor if the car is high enough,after you support the gearbox,remove the mtgs and then the three shift rod nuts on the gearbox levers,remove them, then unbolt the three bolts to gear box tailshaft,do not forget to remove lever first inside the car,then the shift box will drop down.