This Universal Center Drive Set is an option part for the #87633 Wheely King Crawler Conversion set that is designed to fit the HD Final Gear Set. These extra-long 66mm universal shafts are perfectly sized for the long wheelbase rock crawling set-up. These sliding universal drive shafts are also handy items that can be used on custom built cars and trucks. Included in the package are two universal shafts, four screw shafts and a wrench. Must be used with #86336 HD Final Gear Set.