What is the average life of the Timing Chain?

[RickCrew]

I have 1998 993 normally aspiraed with a manual transmision. It has almost 100,000 miles on it. I am in the process of replacing the cluth disk, pressure plate, and thow out bearing. While I have the engine out I'm doing all the other stuff that is hard to do or also require the engine to be remove to do them. I was wondering whether I should go ahead and change the timing chain? I'm the second owner and it appears that the car has been properly maintined. Before I decide to replace the timing chain I want to know what the expected life of it is.

[Britwrench]

Basically on these cars the chains last until the engine needs rebuilding.
Never seen a broken or worn chain on any 993/964 engine. More usual is leakage from the timing chain housing gaskets and power steering drive oil seal leaking on the right cam. If it's a C2 the trans can be removed without the engine being touched.