So I've put 3 sets of packs through the XL so far, only running 4S haven't tried 6S yet. The first run I broke a front left A arm. Replaced. During the down time I shimmed the diffs for when I eventually try 6S and for good measure. Running on dirt/rock construction site area and doing some 5 foot high type jumps I came down nose forward landing the last jump as I had many before it. Then noticed trying to throttle forward the front wheels weren't moving the back wheels were. When I spun the one front wheel with my hand the other spun in the same direction. I took the diff out and found that the diff bevel gear had about 4 or 5 gears with some damage. The driveshaft bevel gear (the one I shimmed) looks OK. The diff outdrive shafts maybe are ever so slightly bent? All other gears look alright. Diff case doesn't look flexed. I did notice that the two top screws in the bulkhead holding the driveshaft bevel gear in (the one I shimmed) are ever so slightly stripped because I ever so gently continue tightening them and they never seem to get tight. Thinking maybe that on the land the force of the shaft forced forward and caused the mark on the larger bevel gear. I don't know. Axial said they'd pay to have it shipped back and fix it up send it back to me. I want to see if drive shafts and new mesh gears might fix it first (since I already ordered them yesterday). Any advices would be much appreciated. BTW I was running the rig stock except for Solar D772 servo and Castle BEC, bypassed the RX for 7.4v power, and homemade steering links using aluminum threaded tubing.