ALL Differentials will have a crush sleeve or a solid spacer to set the pinion brg preload!!! There is NO such thing as a "adjustable pinion nut".
You NEED to keep all your preloads and backlash correct and the same during set up.
During set up I will leave the crush sleeve and pinion seal out and set the preload with the pinion nut only. When the setup is complete I will pull it apart 1 last time using the crush sleeve and seal.