To be dominant in our Trail Truck versus Side-by-Side test, I realized that axle gears and lockers would be needed. In another Samurai I had welded the rear axle and, though it never failed while I owned it, it definitely did chirp the tires on turns. This time I definitely wanted a real locking differential. As a refresher, a locking differential goes within your axlehousing and sends power to both wheels on that axle, whereas an open differential always sends power to the axle with the least traction. There are some selectable locking differentials available for the Samurai, but I chose a less-expensive Lock-Right locker from Richmond Gear for this build. With a phone call to Spidertrax I had the Lock-Rights shipped to my door.