Checking Transfer Case Fluid Level
WARNING: This page is about a different car, the 2001 GMC Safari, 2001 Chevrolet Astro, 2000 GMC Safari, and 2000 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.
Remove fill plug. Check oil level. If oil level is even with bottom of fill plug opening, level is okay. If level is lower than bottom of fill plug opening, add lubricant as necessary.