2003 Chevrolet Tahoe Owner's Manual - Page 404
2003 Chevrolet Tahoe Manual
Page 404 highlights
Rear Axle When to Check Lubricant Refer to the Maintenance Schedule to determine how often to check the lubricant. See Part A: Scheduled Maintenance Services on page 6-4. How to Check Lubricant The proper level for the 1500 Series is from 5/8 inch to 1 5/8 inch (15 mm to 40 mm) below the bottom of the filler plug hole. The proper level for the 2500 Series is from 0 to 1/2 inch (0 to 13 mm) below the bottom of the filler plug hole. The proper level for the 1500 and 2500 series vehicles with QUADRASTEERTM (4 Wheel Steer) is from 0 to 1/4 inch (0 to 6 mm) below the filler plug hole. Add only enough fluid to reach the proper level. What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See Part D: Recommended Fluids and Lubricants on page 6-16. 1500 Series shown, 2500 similar To get an accurate reading, the vehicle should be on a level surface. 5-51