Resting inside of our 2.5-ton carriers was a set of spider gears. Some mud runners and off-road builders on a budget choose to weld the spider-gear assemblies together to create a makeshift spool. A pricier alternative can be had from ARB in the form of a full-carrier replacement Air Locker. We opted for an automatic-style locker from Yukon Gear & Axle. The automatic-style locker is an affordable locker option that provides 100-percent locking-action, while reducing the potential for binding over more aggressive traction aids like spools.