i would suggest to you to buy a kyosho sp2 (top quality) and if you are having a hard time driving it fast , put the 7.5 K3 rear end on the car , inner pivots ,7.5 arms and 7.5 shocks is all you need
the 7.5 rear end has shorter arms and wider inner pivot . better yet just make a spare bolt on rear end.
this combines the nimbleness of the new steering ackerman with the super stable rear end of the old car that was very easy to drive hard and produced faster times .
later guys
Monty