How do you change differential fluid on Chevy Express 2004?

To change the differential fluid on a 2004 Chevy Express, first, ensure the vehicle is on a level surface and safely elevated. Remove the differential cover bolts and carefully take off the cover to drain the old fluid, then clean the surfaces. Replace the gasket, reattach the cover, and fill the differential with new fluid through the fill plug until it reaches the appropriate level. Finally, replace the fill plug and check for leaks.