you can use it on either truck the beauty is you just flip two of the phases and it becomes fwd or rwd. I think that there is a difference between the two. Fwd sort of pulls you along and if you don't have as much weight in the back then if you accelerate to quickly then it skids out. Rwd is fine too. I think its more visually appealing to have rear wheel drive so that when you hold the board you hold the side without the motor. These little differentials cant take a ton of power either I would say 1100w for a 1/8 scale one. I haven't dealt with a bigger one cause i think its unnecessary. They way i have my design setup you can pretty much use any wheels you want. Now granted you will go slower/faster when you change wheels, but it is designed for around 90mm wheels. And what you are talking about is just silly the job if the differential is to spread the power where it is needed. So if you are turning it allows power to still be put through the axles and have one wheel turn faster than the other. I think its a wicked simple idea, I mean just about everyone in the world uses it every day in their car. There is a reason why cars don't use chain drive and belt drives anymore, so why should electric long boards be different. Also there is no reason to shift because electric motors are so good at giving their peak HP at any speed. Gasoline engines need to shift because they cant supply 500hp at 800 rpm. That is the beauty of the electric motor. I don't think you need a more powerful motor too, the motor I am using now is a 6354 and it almost has too much torque for me.