If you increase your truck's tire size, one major component needs to be addressed in order to maintain the engine's torque, horsepower and fuel economy. Increasing tire diameter will affect engine rpm, which affects torque and power. Conversely, changing the rear tire diameter from smaller to larger or vise versa will not affect the rearend differential gear ratio.
An AirDog II DF-165, 165 GPM unit was chosen to supply copious amounts of fuel to the built common rail. Because of the engine swap, Kurtis had to decide whether to adapt a Ford kit to the Cummins or vice versa. It looked easier to fit a Cummins kit than adapting a Ford kit, especially since a certain amount of plumbing changes had already been made to the Ford on the suction side.