I bought a Kona Muni Mula in 1997 and still love riding the bike today. Now I want to replace the old 7-speed derailleur. All new components, however, are 8 or 9 speed (at least the higher-end ones). I do not want to replace my grip shifters or buy a new wheel for a 8/9 speed hub. This takes Sram out of the picture. So what are my options? I would like to upgrade to an XT or even XTR level but can't find any with 7 speed.

Thanks for your feedback in advance!