Hi Stony,
I own the Kraton v1 and have continuously upgraded it, so now it is more a v2 plus additional upgrades. However you asked for specific feedback especially for this truck, and as far as the diffs go v1 and 2 are similar. I was a newbie too and ran my Kraton the first 8 month without doing anything to the shims. I run it mostly on tracks and sometimes for bashing. On the beginning everything was fine running on 4 and on 6S. After a while the rear Diff went of, then the front Diff after 5 or 6 more runs. And eventually the center Diff. So several occasions where I had fixed one Diff and again had to stop because next Diff kissed goodby. I rebuilt them all acc. To manual specs and filled the center Diff with 100 K allowing more wheelies and so. After that the front and rear Diffs really went down on reliability especially on 6 s. If you tighten the center Diff, the torque will be distributed stronger to the wheels that have teacktion compared to a lighter center Diff. Which will allow the power to be distributed to the wheels without tracktion and allow the torque to bleed out in fast spinning ballooning tyres withou tracktion, limiting the max torque which needs to be transferred. Once i put in the 100k in the center Diff I could literally what the front and rear Diff popping the cloggs every 6 to 8 runs. It was then I decided to give the shimming a try. i did that 6 month ago and have never had an issues since then. Even on Wheelies, hard braking from full speed to stop or what so ever. So on a nutshell I would definitely recommend to do internal shimming (shims in the cage into of the o rings) and external shimming (inlet gear and on one or two side of the bearings. Make sure that a minimum play i still guaranteed and the gears are not running too tight afterwards. You can determine this by turning the Diffs with hand. If you feel a little resistance and the gears meshing unsmooth that means too much shims in. Take one out again should that be the case. If you build the Diffs internals and are new to it. I recommend to put the shims in and tighten the screws without putting any Diff fluid in. If it's too loose or too tight you will have to open them again and get it right, -and it is just a mess if you have all that oil Messing around. One you have it right. Put the oil in and do final assembly. Hope this helps best regards Derrick