You can probably run it without one or buy a new one from Santa Cruz. As long as the wheel is aligned and tight, I think you should be fine.
As far as the year, there should be a serial number on the bottom bracket shell. The first two digits should give you an idea. My Chameleon started with 99 for 1999. My Heckler started with 2K for 2000. I am guessing the years after where 01, 02, 03, etc, etc.