I probably shouldn’t post in this thread as I have no L35 or experience or parts diagram to rely upon.... but one of the specialties I was trained on as a young Toyota Tech was differentials... and one of the tedious issues was pinion-gear-to-ring-gear preloads and measurements.
The pinion gear depth determines where the gear teeth interface the ring gear. That is controlled by shims, crush-sleeves, pinion bearing depth, or all three. Many pinions have an identifier on the big-end engraved so that when replacement time comes a pinion with identical depth measures is used. Other designs rely upon those shims and crush-sleeves.
If you replaced the old pinion with a new one of unknown dimension then you’ll have to go thru all the trouble the OEM had to determine at original mfr. This will likely require different shims and/or torque-values (if a crush-sleeve is used.)
With a tractor ...gear running-noise may not be the issue as it can be in an automobile... but I’m guessing you’ll be happier if you can locate a unique identifier on that old pinion and get the same one on the new pinion.
Let’s also mention that if those bearings are not completely seated on the pinion shaft (like using a shop press to properly seat the bearing) then that dimensional change will affect re-assembly also.
Hope this helps.