The TeraFlex HD44/CRD50 differential covers are designed to offer extreme protection from rocks, obstacles and other debris on the trail. The cover is cast from the same high-strength ductile-iron as our HD axle housings. The cover is over 3/8? thick to ensure protection. It also offers two fill plugs for use in standard or high pinion D44 housings, or when the pinion must be rotated in extreme applications.