If the castle nut is too low to intercept the cotter pin, in my driveway it'd get a spacer/washer to boost the nut to proper height...
...AFTER I was sure that the male taper in the stud is compatible with the female taper on the part it's secured into.
This is not something I'd leave to a fancy spring-pin.
Grease compatibility:
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and/or
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And there's a dozen more charts for those who choose to research this.