I just started building my YZ-2 yesterday. I bought the ball diff, but when I assembled the gearbox there is a ton of side to side play in the diff. What shims are you guys using to eliminate this? Also are there any other parts needed when using the ball diff? Also, are the machined pistons a worthwhile upgrade? Trying to just make one more order with A-Main. I am looking forward to getting this on the track next Friday night at LSR.