Most spindles have two cotter pin holes in them, 90 degrees apart. The 6-slot castle nut only has to be turned less than one flat to align a slot with one hole or the other. It won't hurt to drill another cotter pin hole in the spindle, if yours only has one hole.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!