Yukon Grizzly Locker, Ford 10.25" & 10.5" with 35 splines.. The Yukon Grizzly Locker is the ultimate in mechanical locking differentials for street, off-road, and drag racing. Grizzly Lockers provide 100% power to both tires, while still allowing for disengagement while negotiating turns.. Everything about the Yukon Grizzly Locker is hardcore, its casing and gears, its advanced gear tooth design, and its impact on traction and performance. The Yukon Grizzly Locker is a mechanical positive-locking differential thats engineered for rock crawling, serious trail running, off-road racing, and drag racing. The unit provides 100% power to both tires, while still allowing for disengagement while negotiating turns. The Yukon Grizzly Locker is a patented design that features innovations that make it tougher than the competition. Its inner clutch teeth have a larger radius at the base, which offers up to 350% greater strength versus back-cut designs. The Grizzly Lockers larger teeth also resist breakage caused by shock-loading or catastrophic axle failure. Its a serious piece of mechanical engineering for serious driving situations.