I realize this discussion is an old one but my 99 with 62k miles needed a new expansion tank. Thanks to the messages on this board, I was pretty well prepared to tackle the job and save some $. The pictures and messages were a big help. The job took me about 4 hrs to complete and I used car ramps to elevate the rear end. It made it easy to do an oil change in the process. The expansion tank, new 01 cap and a gallon of Porsche antifreeze cost me about $228.00 from Sunset. I couldn't believe the price difference for parts between the local Porsche dealer and Sunset.
The earlier postings describe the proper steps. It's definitely easier doing the job from under the car - using ramps if you have them. A good pair of notched pliers will take the pressure fitting off the hoses quickly. It is necessary to remove the bottom bracing and covers to have a good look. Another tip is to drain the coolant only enough to empty the expansion tank ~3/4 - 1 Gallon should do it. Save some money on the antifreeze.
My replacement tank didn't have the hole drilled out for the oil dip stick. Not a big deal to drill the opening but be aware it might happen. I believe my replacement tank was a .10 - not sure if that means version 10. Crazy.... should have been a part recall or field modification from Porsche due to the poor quality of this tank.
Good luck and thanks again for all the info guys.
Enjoy the ride.. Allan