Timbren kit GMFK15A fits the 2000 GMC Yukon XL 1500 4wd.
Timbren kit GMFK25S fits the 2000 GMC Yukon XL 2500 4wd.
The kit you will need will depend on if you have a 1500 or 2500 Yukon.
Feel free to call us at 1-800-358-4751 if you have any additional questions.