Classic/Antique Car Repair: Leaking Pinion Seal, pinion bearings, pinion nut

Question
Brad,

 In a previous question you advised me on getting the overdrive working on my '49 Packard.  That is in good shape now, and working well.  Thanks again.

 My question this time is in regard to a leaking pinion seal in the same (1949 22nd Series Packard) car.  I have replaced the seal three times in the last year (trying to get lucky, I guess), but the seal always winds up leaking again.  I have used seals from two different vendors.

 When I bought the car the rear end was dry.  I don't know how many years it had been that way.  There is a whine from the differential at high speed, and I figure maybe the bearings aren't all they should be.  I try to keep it filled with 140W GL4 gear oil.

 After driving the seal into place I torgue the nut on the companion flange down to 200 ftlb as specified in the manual.

 Do you have any suggestions as to how to approach this leaking seal?

Answer
Hi jay, welcome back. There are several things that I would look for. First would be a ring worn around the flange that is letting the seal leak. Number two, check the pinion and see if you can move it side to side. The pinion bearing adjustment is via a collapsable sleeve that allows the two pinion bearings two preload when the pinion nut is tightened. My way of taking off a pinion nut is to mark the nut and count the number of turn to remove it. Then when reinstalling  just put it back the way it was aligning the marks. But now probably the crush collar is all crushed out and will need to be replaced and probably replace the pinion bearings and reset the pinion preload. What do you think?
Brad