well over at mtf, they say u need ti shim ur diffs, cause if not some diffs will end up eating ur gears, luckily mine didnt need shimming
lol taiwanese kid, if u think think assembling the alum tranny is easy.. its not lmao, i put on the spur gear, then i realized i forgot the motor mount, then realized i forgot to screw in the tranny, another time to disassemble the spur, lmao took a very painful and angry 30 mins to get it right, maybe i shoulda followed the instructions tthey provided lmao!!
as for gearboxes, the 3r gearbox is one of the best, make sure you get the one that comes with the bearings for the spur shaft, its worth it, i nearly doubled my driving time with just those 2 bearings(brass kinda creates friction lol)