Section 262 (Drive Axles - Full Floating Axle): Lubrication
WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 GMC Sierra, 2002 GMC Savana Special, and 2002 GMC Savana Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
Fill differential with Axle Lubricant (P/N 12378261, Canadian P/N 10953455) SAE 75W-90 Synthetic or equivalent meeting specification 9986115. Remove the rear axle fill plug. Inspect the lubricant level. The lubricant level should be between 0-0.4" (0-10 mm) below the fill plug opening. If the level is low, add lubricant until the level is even with the bottom edge of the fill plug opening.