2011 Chevrolet Silverado 1500 Regular Cab Owner's Manual - Page 440

10-34 Vehicle Care Four-Wheel Drive Transfer Case When to Check Lubricant Refer to Scheduled Maintenance on page 11‑2 to determine when to check the lubricant. How to Check Lubricant Manual Shift Transfer Case A. Fill Plug B. Drain Plug Active Transfer Case A. Fill Plug B. Drain Plug To get an accurate reading, the vehicle should be on a level surface. If the level is below the bottom of the fill plug hole, located on the transfer case, some lubricant will need to be added. Add enough lubricant to raise the level to the bottom of the fill plug hole. Use care not to overtighten the plug. Electric Shift Transfer Case A. Fill Plug B. Drain Plug