most early ag rearends came with little more then bushings in the differential carrier,fine for most farm work but pulling adds a lot of stress to equipment that company engineers never planned for,needling is essentially putting bearings in the differential spider gears and sometimes thrust bearings on both sides of carrier-makes for a much saner ride down the track! can tell you that rack and pinion steering components do not fair well when your tractor decides to walk side to side in alarming speed!
Do a search for needled rear end, has been a topic on this site many times. Go to builders look at Englers web site had a good description of parts to go in differential (cross). Improves the tractors ability to go staight.
