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. This high-strength rear axle shaft kit from Alloy USA fits 79-93 Ford Mustangs with a 4-lug 31-spline 8.8-inch rear axle.
