To start off I didn't find any threads that answered my question. haha. On the rear axle of my bobbed truck the pinion has some slop in it. Maybe an 1/8th inch or less front to back and i can push the drive shaft up and down and feel and see the pinion move. I first noticed this a month or two ago but i havent driven it much and it hasn't got any worse. I tried tightening the pinion nut(s) with a break over but they wouldnt move a hair. Any ideas? I have a spare axle as well.