Not sure your location but Quality trailer in Freeport MN will sell just the axle. They sell the axle you want, but they aren’t cheap thinking like 1200 or something last I checked. You could buy a standard torsion axle for about 500 cut arms off buy 2 pieces of flat cold rolled steel mill the square hole saw the spindles out (every attention to detail required on them parts, likeness and pitch) and weld back together. I did that worked great but I’d just pay the extra money next time.