I don't want to be breaking some cross-posting rule but I really need an answer and with the depth of knowledge here cannot believe someone doesn't have a answer.

I have a rear-end whine during decel. Reading through the threads:

How to replace pinion seal 2004-2008

https://www.f150online.com/forums/20...04-2008-a.html

Pinion flange torque? 9.75

https://www.f150online.com/forums/20...ue-9-75-a.html

and others I think I have a fairly good understanding of the problem.
My question is if I check the preload now as outlined in the threads above
and it is lower than (8-14 in lbs -used) can I carefully tighten the pinion nut
to bring it up into the proper range. Could this correct the problem and stop
the whine?

In a (maybe) related problem I may not have put the driveshaft back in the
same position on the pinion shaft flange when I replaced the u-joints awhile back. The book (Chilton) says the driveshaft has to be returned to the same place to maintain the "dynamic balance" of the driveshaft. As there are only two ways (4?) for the driveshaft to bolt up how do I pick the right one to restore the balance?
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I take it you have no whine or noise on acceleration? A whine on decel generally alludes to problem with the outer pinion bearing (spalling or fatigue). The first recommendation would be to look for lube leaks anywhere on the complete axle assy. Lube leaks generally point to the origination of the problem area.

Check for end play at the pinion flange. If there is end play: we have a problem. If end play is present, be very careful re-tightening the pinion nut. Over torque of used bearings will only accelerate spalling of the pinion bearings. Even many of us professionals occasionally error when dealing with used pinion bearings.

 

Thank you. I have NO leaks anywhere on the rear diff.