Hawk has the 6.5:1 and the 4:1 transfer case kits.
Trail Tough has the 4:1, 4.8:1 and 6.4:1 kits.
Rocky Road has the 8:1 and 6:1 kits, but make sure they have the 8:1 in stock before you order it. Otherwise you could be waiting a while.
Asian Auto Parts of Arizona has 4.1:1, 4.9:1, and 6.4:1 kits.
Roadless Gear has 4.1:1, 6.1:1 kits.
Most of the companies offer rebuilt transfer cases if you don't want to do it yourself.