A typical failure on 911s is for the rear swaybar tab to rip off.  This results in a clunking noise, and non runctioning swaybar.

Here is the remaining part of the mount.

The factory offers a repair kit for a bit over $100 per side.  Installation is about 2 hours per side.
You need to remove the entire assembly and install the new reinforced mount.

We take a simpler and strionger approach and make a new mount fromscratch if it is badly damaged or simply reinforce unbroken mounts.
 

First we make up a plate from 1/8" mild steel, and weld captivve nuts.  The factory units are 16 guage steel.

Next, clean the effected area

Thn weld the new peice in place.
 
 

Then reinforce the hell out of the back side.  THis is what the factory did withthe replacement kit, but ours is much more substanital and much less intrusive.

We always do both sides.  Here is the undamaged driver's side.  After removing A/C lines, we tape over the DME harness with several layewrs of reflective tape to mitigate radiation form the MIG welder.

Again, cleaning to bare metal is key to a decent weld.
 

And here is the reinforced bracket.  One thind that was nopt shown was that the captive nuts were also rewelded.  This is going nowhere.