Transfer Case
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1988 Ford Ranger, 1988 Ford Pickup, 1988 Ford F-Super Duty, 1988 Ford Econoline, and 1988 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
Remove filler plug. If fluid drains out or is level with opening, replace drain plug. If not, fill until fluid is level with filler plug opening.