Change the slave cylinder at the same time. Going from my personal experience, as well as several other BBS members experiences, They (master and slave cylinders) tend to fail at about the same time. Mine failed a week after I replaced the master cyl.
the parts are $72.00 for the master cyl, and $59.00 for the slave cyl.
http://www.pelicanparts.com/catalog/shopcart/944M/por_944M_clutch_main.htm
click on CLTH CYLS (on the left side)
Mike
[This message has been edited by mike944 (edited 08-16-2001).]