Front HS bulkheads enable diff height adjustment making use of eccentric bushings. Within the front side gearbox, the diff height has a 2mm modification range by which 2 Dot is for center diff position. The diff height adjustment is an important set-up capability which allows quick set-up adaption for either Carpet or Dirt songs. Carpet version runs with reduced ride height and also to keep consitently the drive shafts directly the differential is positioned in top place. Dirt version operates with upper trip height and to keep carefully the drive shafts right the differential is positioned in lower position. Fits XB4'21
