High tensile strength 4340 Chromoly is heat-treated, tempered and induction hardened to produce these heavy-duty axles that are up to 40 percent stronger than stock 1040 axles. Each axle shaft is backed by Alloy USA's exclusive ten-year warranty Our front axle shaft kits include everything you need to complete the job: both passenger and drive side inner and outer axle shafts, seals, U-joints and clips.