The threads for loading the pinion bearing, 2 large nuts with a lock nut with tabs between the nuts, is on the shaft. To replace the pinion bearings or pinion race requires removing the end castle nut, pulling the pinion off the shaft in order to take the unit apart
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This is why the pinion was redesigned and threaded on the later drive shafts.
Also the pinion on the early drive shafts has 10 teeth and the ring gear has 37 teeth; the ratio was 3.70, the later standard rear end ratio was 3.78 with 9 teeth on the pinion and 34 teeth on the ring gear.
If your pinion gear is good and usable someone may have a need for it.
Ron