Transfer Case
WARNING: This page does not describe the selected car, but rather 54 other vehicles, including the 1994 Geo Tracker, 1994 GMC Yukon, 1994 GMC Vandura Special, 1994 GMC Vandura, and 1994 GMC Sonoma. However, it is still accessible from the selected car via links, so may be relevant.
Remove filler plug. Check oil level. Lubricant should be level with bottom of filler hole.