So I tried this trick of double 15X21 bearings that some people are doing in the axle carriers to be able to use the stock LST XXL diff cups. I wanted to see if it worked with the stock Traxxas axle carriers and the rear Traxxas extended arms. It turns out that it all came together beautifully. One thing I did to push the CVD even deeper into the diff cups was to drill the holes for the pillow balls 3 mm deeper then they are. Then I screwed the pillow balls about 1.5 mm deeper which brought the CVD axle pin deeper in the cup where I wanted it. There is now three bearings supporting the axle, and the outer bearing and the most inner bearing are now 5 mm more apart so it should give a lot of support to the axle. Now being able to use the stock LST XXL diff cups cuts down on the amount of mods to be done and the parts needed.