Axle shafts are machined from heat-treated Chrome moly steel, triple step chrome-plated, then machine polished and ground to a finish tolerance of + or -.0005" Rear axle nuts are welded to the shaft with a full weld penetration, then machined smooth before final machine polishing and plating Axles are 3/4" diameter Works on 1958-66 models equipped with haydraulic drum brakes on the rear