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!