Yukon Gear Dana 44 and GM 8.5in Front Spindle Replacement Fuel Delivery>Fuel Systems Using progressive-rate springs means that

Using progressive-rate springs means that instead of a hard stop at the end of axle travel the axle energy will be absorbed when bottoming-out producing smooth

Fits left and right sides

fully-welded steel construction that distributes weight evenly across a broad footprint

To control the rear end in specific ranges of travel

Yukon Gear Dana 44 and GM 8.5in Front Spindle Replacement Fuel Delivery>Fuel Systems Using progressive-rate springs means thatYukon Gear & Axle front spindles are manufactured to tight tolerances and feature a deeper heat treatment at the bearing journals compared to OEM for greater strength and durability.