Hey, this one has me stumped, yesterday my truck just flat out quit pulling, to my surprise, the the nutt on my spur gear/slipper, had backed off, enough to the point, of it not pulling, got it back home and tightin it back up, right off the bat, it happens again, so i take it off and inspect the nutt and threads on tranny shaft, all seems well, but i replace the nutt anyway,take the truck out today, half a tank, and it does it again,,, any ideas