Straight from the horse's mouth:
"OK guys, here is the story.
The Novak system WILL bolt up and WILL work. You have to leave the pinion extended off the end of the shaft. The pinion should turn true and fit far enough onto the shaft to remain secure. The only issue revolves around the shaft of the Novak motor. Stock up on rotors, as you will probably break them if you run hard (they could even break on the old E-Maxx, this is not breaking news- no pun intended). We pictured the Novak system simply because it was the only true bolt in, readily available system on the market at the time. Hobbyists wil probably see these companies evolve to produce systems compatible with, and able to withstand the power necessary to propell the truck.
-You cannot use a dished spur, it would interfere with the right transmission mount.
-Post #57 has the best solution in this thread so far, or until Noval offers a 5mm shaft. However, two things to note:
1) It will need to be run without the gear cover (both upper and lower parts).
2) The motor plate is designed to provide additional support for the input shaft bearing on the trans case-this is a snug fit. Moving the plate may still work, but we cannot promise this as we only tested it as designed.
Traxxas produces innovative new designs which tend to cause others to evolve. There is a short period of time following a new release that sometimes requires special procedures in order to achieve the desired results. As time goes on, hobbyists will see more and more readily available products to achieve those same results.
Zinno a Traxxas employee