AustinWestern pacer 300

Hello All, Regarding A 1969 Austin Western Pacer 300, does anyone know if the fine spline constant velocity joint, that is in the steering knuckle on the rear axle, interchanges with the one on the front axle? Are there certain years of the Clark branded graders that share this part? What range of years could be a donor machine for this part? I'm searching for this part for my machine. Thanks for any help.

AustinWestern pacer 300