the shift boot on a 99 has a leather knob, but the boot is vinyl. you can see where it is glued together. buy a newer, one peice leather boot & knob. if you have a 5 speed make sure you get one w 5 speed markings. the 6 speed is identical except the markings for gears. the 6 speed is for the box s and 911. here is one on ebay.
http://cgi.ebay.com/ebaymotors/Porsche-Boxster-Black-Leather-Shift-Knob-New_W0QQcmdZViewItemQQcategoryZ33703QQitemZ8051976 763QQrdZ1QQsspagenameZWDVW