Normally, when removing a 489 yoke for a seal replacement, etc. one can simply mark the relationship of the pinion threads with the nut so that the nut can be tightened to its original position thus retaining the original bearing preload.

But the replacement yoke might have a different dimension from the nut/washer surface to the rear of the yoke so the pinion/nut marking doesn't guarantee the same preload; but I'd wager that the dimension difference, if any, is so slight as to be negligible. I'd just mark the pinion thread and nut with a center punch, change the yoke and tighten the nut to that mark with some red Loctite.