Transfer Case
WARNING: This page does not describe the selected car, but rather 13 other vehicles, including the 1994 Ford Ranger, 1994 Ford Pickup, 1994 Ford F-Super Duty, 1994 Ford Explorer, and 1994 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Under normal driving conditions, replace transfer case fluid every 60,000 miles. Under heavy 4WD driving conditions, replace fluid more frequently.