I believe they are Husaberg specific. I would think they would still be available from your dealer. They are alittle on the pricey side if I remember correctly.
Just purchased a full clutch set for my "96 FE501 from BOSS. Friction plates came in a KTM Package. If you're in the NW. U.S.A. I know he can help. www.offroadboss.com