Hi,
you can still get the panniers through Triumph, although supplies are intermittent. They do come up on eBay on a regular (if long time between) cycle. It's the steelwork that goes into the subframe., the indicator extenders and assorted rubber bits that is the real problem. Most people selling on either don't know about this stuff, or can't be bothered to remove it all.
There are some instructions on another site (
http://www.triumphnet.com/
- Look under 99-04ST>FAQ>Inst/mods/Upgrades>2 box Pannier) that show all the parts required for the 2 box pannier kit and 3 box as well
there is also a thread that covers off some of this
Mounting Panniers
Hope this helps
Rexx