To help prevent leaks, you can apply some RTV silicone sealant (gear oil rated compound, Toyota FIPG orange or Permatex Ultra-gray should be good) to the splines of the pinion shaft prior to sliding the pinion flange on. Reinstall the flange, washer and nut. If the old nut is in decent shape, it can probably be reused, if not a new nut is available from the dealer. Tighten the nut the same number of turns as it took to remove it and tighten no more than about 90 ft.lbs. or until the stake mark aligns with the groove in the pinion shaft. Check the flange for play and for being overly tight. If it feels OK, re-stake the lip of the nut with a punch and hammer to keep it from loosening up, then re-install the driveshaft bolts, tighen to factory spec. (~54 ft.lb.) and you are done. If you drained the gear oil, be sure to replace it before driving, approx. 2.5 qts. of GL-5 should do it.   (8/8)