If you are running brushed motors, you can use Traxxas XL-5 or XL-10. They are more than enough for the King.
Glad I could help:tmb I would have helped a lot sooner, but I work. And the computer caught a virus. And I work. Try and remember that everyone here does not own a WK, and this is only a hobby so time is limited. We cannot stop by as much as we'd like.
I would like to add, though, that William G is absolutely right.