Search, lots of info. Short story is your '98 has the "more reliable" of the 986 IMS designs. Conventional wisdom would be to change it when you get the chance. The most opportune time is at clutch change time, should add around $1k to the job. Any mechanic that works on these cars should know this and advise you of your options.

Thanks Runjmc2.....
Ive owned a few cars with standard transmissions but never long enough to have any clutch work done...possibly because I'm such a wonderful driver but more likely just dumb luck with a bit of skill thrown in.

What's the typical life expectancy of a clutch? (I know much depends on the driver but a AVERAGE range of miles would be helpful) I currently have 74,000 on my 98.

Thanks,
Rob

mine was toast by 70K miles, as was the flywheel. At which point I upgraded to the LNE dual row IMS bearing and replaced the RMS with the Cayenne unit.

Pricey repair, first time I ever forked over $3K plus on anything that wasn't an engine or transmission rebuild. My original dual row bearing looked solid from the outside but that's not really a good metric to go by.

Even if my clutch hadn't been on its very last legs I would have have done the IMS bearing and clutch prematurely. No point putting it off in my mind just to save a few hundred bucks in extra clutch mileage. This upgrade is one of the few that both addresses a weak spot while providing utility -- you get a new clutch out of the way and are good to go for a long time.