I was trying to verify tdc on my car the other week, and since I’ve owned the car the timing belt has moved back and forth on the gears. During the process I noticed the washer portion of the crank gear could rotate freely around the back of the keyway on the crank, and that my udp had become knife edged. I replaced the gear with a 1 piece unit off a 03 svtf engine and with a new udp from ZXTuner the timing belt stays in 1 place 
Couple Pics
timing belt crank gears:98 left/ 03 right
http://i174.photobucket.com/albums/w118/mellowness65/2010-03/P4130354.jpg
http://i174.photobucket.com/albums/w118/mellowness65/2010-03/P4130356.jpg
Essy UDP’s New vs old
http://i174.photobucket.com/albums/w118/mellowness65/2010-03/P4130358.jpg
http://i174.photobucket.com/albums/w118/mellowness65/2010-03/P4130359.jpg
http://i174.photobucket.com/albums/w118/mellowness65/2010-03/P4130360.jpg
Timing belts: Old v. New, You can see the blue of the gates racing belt where the edge of the udp was chewing thru it
http://i174.photobucket.com/albums/w118/mellowness65/2010-03/P4130361.jpg