Kit came complete and wasnt too hard to install. Had to fabricate a new engine mount to raise the engine enough to add the gear box. The forward gear output changes the final gear ratio by 30%, so you might have to regear. I am running the 10 tooth sprocket that came with gearbox with my factory 60 tooth axle sprocket. With this setup my daughters go kart is really slow but it crawls really well. I will probably have to change out to a 48 tooth sprocket to get close to stock ratio.