Built for serious GM-14 bolt axle builds, this Yukon 40-spline Grizzly Locker sends 100% of available torque to both axle shafts under load. Its a major upgrade for 10.5" 14-bolt axles that have been converted to 40-spline shafts and are pushing larger tires, heavier loads, or extreme terrain- whether you're running a one-ton truck or a rock crawler.

The patented gear design uses larger engagement teeth and improved tooth geometry to significantly increase strength and reduce failure points. Built with 8620 steel internals, this unit is made to survive hard trail use, competition environments, and heavy-duty applications. It automatically unlocks during turns for improved drivability while maintaining full traction when needed.

Includes:

• (1) Locking differential for GM 10.5" 14-bolt (40-spline)
• Fully assembled internal gear set

Specifications

• Fits GM 10.5" 14-bolt differential
• 40-spline axle compatibility
• Carrier: 4.10 and numerically lower gear ratios
• Automatic mechanical locking differential
• 100% torque transfer under load
• 8620 steel internal components
• Patented gear design for increased strength and durability
• Larger internal teeth to resist shock load and breakage
• Does not use factory thrust washers
• Differential Cover Bolts: 14

Fitment

• Requires 40-spline axle shafts (aftermarket upgrade)
• Designed for 4.10 and numerically lower gear ratio carriers
• Verify carrier break and spline count before purchase

Tech Insight

Upgrading a 14-bolt axle to 40-spline shafts significantly increases axle strength, but also requires a differential that can handle the added load. This locker is specifically built to match that level of strength, making it ideal for extreme builds running large tires and high torque.

Mechanical lockers like the Grizzly provide consistent traction by locking both wheels under load, which is critical in off-road environments. Proper setup and inspection are key to long-term durability, especially in high-stress applications.