drive shaft rubs on mufler now

Are there pieces one can install to safely limit the downward travel of the axle? I am just thinking at some point he is going to be smacking the exhaust and damaging it otherwise.

I say this while installing a rear differential in another vehicle. While at the dealership getting parts I talked to a couple mechanics who explained that the vent on the case gets destroyed when there is too much travel allowed (worn mounts). Similar idea but in this case it would be the exhaust getting damaged.

Just a thought.