Transfer Case
WARNING: This page is about a different car, the 1989 Jeep Wrangler, 1989 Jeep Wagoneer, 1989 Jeep Grand Wagoneer, 1989 Jeep Comanche, and 1989 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
Check transfer case fluid level every 7500 miles and replace fluid every 30,000 miles or 30 month intervals.