Alloy USA uses high strength 4140 Chromoly in all its Jeep axles Our axles are heat-treated twice and induction hardened to produce these heavy-duty axles that are up to 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 an exclusive 10-year warranty! Rear axle shaft kits include everything you need for your installation: both passenger and drive side shafts, seals, bearings and wheel studs. and wheel studs.