This came off of my 40,000 mile 2000 Boxster S 6-speed. The inner portion of the mount is almost completely seperated from the outer housing. This car has seen several standing-start acceleration runs in competition (ProSolo) so it's not surprising that it's in such bad shape.
Symptoms were a noticable vibration when simultaneously cornering and accelerating or decelerating. Also rough shifting, expecially in cold weather. I do not know exactly why shifting improved as much as it did since the transmission and engine are linked and the transmission is shifted by cables - but it did.
Replacement was not difficult and took about an hour and a half. No special tools required.
