It can be done, but it may not be a good idea. If that mount is worn is that fashion, your trail arm bushings may also need replacing. That's also a good time to replace seals and check/adjust backlash and replace the center rubber boot. There are also sleeves that may need replacement at the right wheel arm pivot points. Finally, when you replace that center mount, you need to adjust the position of the vertical arm, and it's easier done with the axle out of the car. It may look daunting to drop the entire rear axle, but it is in fact easier to work on the axle out of the car rather than fighting with two half axles dangling under the car.
