If you have the f4.6 you have to pull the roto start and the backing plate on the motor and inside the crank case the oneway will be right there. Pull the old oneway out and silde the pin of the new oneway in the hole where the crank and the pistion rod meet and put it back together. with the .25 pull the roto start and the one way is right behind it. You can also go to
www.hpiracing. and down load the the book on your truck and that can help you too.