1963-1979 Half Shaft U-Joint Flanges tend to get a bit tweaked or warped when changing out old U-Joints. Be very careful and only use enough force to get the job done. If U-Joint rotation feels rough when replacement is completed, the flange is likely damaged and will wear your U-Joint out much quicker. This direct replacement flange connects the half shaft to the rear wheel spindle flange.
The construction and design of this flange makes it vulnerable to damage when replacing your U-Joints. Because of this, it must be bolted to a plate to prevent distortion during U-joint installation. The friction fit of the cups requires enough force during installation to warp the flange if it is not bolted during the pressing operation.