Redesigned super-strong BACKSIDE bulkheads are narrower to go the arms more into centerline to produce more traction also to provide a more substantial array of track width modification. The bulkheads have in fact an excellent fit towards updated differential and they are strengthened to boost the reliability. The XB4 bulkheads allow super-fast & easy diff trade and servicing by dismounting simply 4 screws through the front part from the bulkhead and base from the framework. This super-fast diff access can be acquired at both front & back. The bulkheads have actually in fact minimized ball-bearing play, leading to increased gear teeth lifespan and minimized gear stripping.