Front HS bulkheads enable diff height modification utilizing eccentric bushings. Inside the front part gearbox, the diff height has a 2mm modification range through which 1 Dot is for top diff destination. The diff height modification is a vital set-up capability that permits quick set-up adaption for either Carpet or Dirt songs. You will find 3 different angle configurations for adjustment the front drive train. Carpet variation operates with minimal journey height and also to keep carefully the drive shafts appropriate the differential is put in top place. Dirt variation operates with top ride height also to keep the drive shafts appropriate the differential is put in lower spot. Fits XB4'21