Its like Doc stated ... nothing like hearing it from the horse's mouth, if you would rather hear it from a forum member then maybe I could give you some reassurance. If Klockwerks is listing a fender for a 2000+ they are telling you that is infact what it will fit. If there was no change through the years in the mounting holes used to fasten your strut to the frame & fender it may well say 84-2000.
You can almost bet that the 84-99 struts are indeed different from the 2000+, It may not be significant in the mounting holes to the frame & horns but it may well be the remaining holes where the pre '99 fender mounts to the strut, thats where the difference could be.
I would do as Doc has already suggested give the boys at Klockwerks a call, it will may save you alot of aggrivation down the road & peace of mind your getting what ya want.
We never even said a word,
We just walked out and got on that bike
And we rolled...
And we rolled...... clean out of sight
2000 FXST - Carbed