You should post your question on the IH Farmall board of this site. See link.
All parts (outer bearing, spacer, bull gear, washers, innder bearing) on the rear axle are held together by a bolt that screws into the inner end of the axle. Parts from any A, Super A, International A or AV will fit. Left axle is identical to right axle. Left final drive is NOT identical to right final drive.
Replace parts as necessary. Peek up in the final drive to check the condition of the pinion on the differential shaft.