differential

:help Changed my rear diff fluid today. Bought the truck 3 months ago and was concerned about the rear diff because that's what went on my 98 K1500($750 repair) before I stopped driving it, so I am now paranoid by differentials. Replaced with Lucas 75W-90 synthetic(Hopefully I do not regret...

so yesterday i noticed while turning that the truck squels and drags one tire when going around a turn like the rear is locked up? what could it be it disengages some times and turns with out an issue but some times and makes so weird noises especially when backing up. popped the plug fluid was...