Front HS bulkheads enable diff height modification utilizing eccentric bushings. Inside front side side part part component gearbox, the diff height has a 2mm modification range which 2 Dot is for center diff spot. The diff height modification is an important set-up capability enabling quick set-up adaption for either Carpet or Dirt tracks. Carpet variation operates with lower journey height and keep the drive shafts appropriate the differential is devote top spot. Dirt variation operates with top journey height as well as keep consitently the drive shafts right the differential is devote paid down destination. Fits XB4'21