Spartan Locker for Dana 30 . 27 spline axles . with heavy-duty cross pin shaft. The Spartan Locker is a lunchbox locker that delivers reliable . 100% lockup traction at a low cost. It's design does not use the thrust washers and has a revolutionary spring and pin design that makes installation a snap!. The Spartan Locker by USA Standard Gear provides reliable traction at a low cost. The Spartan Locker's patent pending design replaces the spider gears in a standard carrier case . does not use the thrust washers . and has a revolutionary spring-and-pin design that makes installation even easier! This style of locker is known as a lunchbox locker because of its compactness. The Spartan Locker features heat-treated 9310 steel internals for enhanced durability. The advantages of utilizing a Spartan Locker are its 100% lock up and affordability . both in initial cost and installation cost. The install is easier on the wallet because the differential does not need to be removed for installation. In fact . some enthusiasts install the unit themselves versus taking it to a shop.