Front HS bulkheads enable diff height modification using eccentric bushings. Within the front component gearbox, the diff height has a 2mm modification range by which 1 Dot is for top diff location. The diff height modification is an essential set-up ability that permits quick set-up adaption for either Carpet or Dirt tracks. You will find 3 various angle configurations for modification the front drive train. Carpet variation runs with minimal journey height and to keep carefully the drive shafts appropriate the differential is devote top place. Dirt variation runs with top trip height also to keep the drive shafts appropriate the differential is invest lower spot. Fits XB4'21