Alloy USA uses high strength 4140 Chromoly in all its Jeep axles. Axles are heat-treated twice and induction hardened to produce heavy-duty axles that are 35% stronger than stock 1040 axles. Alloy USA uses the latest cold spline rolling technology to produce splines that are stronger than traditional cut splines. Our shafts are covered by a 10-year warranty! Rear axle shaft kits include everything you need for your instal: both passenger and drive side shafts, seals, bearings and wheel studs.