don't worry about it. tighten it 'till there's no more slack then tighten it more for the preload (rotational torque). the spec. for the preload might be with no pinion seal installed. if that's the case then your crushing the sleeve to attain the correct preload then taking it back apart again to install the seal, then reassembling and retightening it. the trick is to set the preload with a used nut then doing the final assembly with a new lock nut so that you'll know it will stay tight. not easy to get it exactly right by the book. i found it was easier to throw the book away and do it by feel. in tightening this you're pulling the inner pinion bearing up against it's race. you can tighten it from here to kingdom come and never pull the pinion any further forward so this doesn't affect the gear pattern it only sets the preload on the pinion bearings. how would you tighten a front spindle nut? same goal.