When I worked at a hobby shop I had a guy bring in his Platinum Revo for me to look at. He rebuilt the whole car from ground up and managed to put both, front and rear, diffs upside down. So now he had a truck that had 2 speeds in reverse and no front drive. What made it even funnier was when he told me that he tore apart and assembled the transmission something like 10 times.
Oh yeah, the diff cup bearing.......been there man. If I had a dollar for every time I done that.....