Air Locker Differential Dana 70/80, 32 SPL, LOW SPEEDLocking Traction for Your Workhorse Dana 70. Whether you are driving a 7. 3L Powerstroke Ford F 350, a 5. 9L Cummins Ram, or a big block Chevy 3500, your truck was built to work. However, the factory open or limited slip differential in your rear Dana 70 often lets you down when traction gets scarce. The ARB RD173 Air Locker is the ultimate traction solution for these classic heavy duty platforms, giving you the ability to lock your rear axle on