Front & rear bulkheads feature a horizontal split design (HS) to retain easy diff access while adding the valuable new diff height adjustment. The unique design of the bulkheads uses an inline bushing to alter the alignment and height of the bevel drive gear. In addition to accommodating the diff height adjustments, it also allows the front central driveshaft to operate with a reduced angle for less friction and wear on the CV joint components and improved driveline efficiency. The XB4 bulkheads allow fast and easy differential access for setup changes or servicing by removing only 4 screws from the upper gear box cover while the lower section remains mounted to the chassis. This super-fast diff access is featured on both front and rear gearboxes. The super-strong, narrow bulkheads provide the needed clearance for the redesigned suspension holders with increased set-up range possibilities. Fits XB4'21
