Thats what I was afraid of. Are there any other gearboxes that will fit the Leo drive sprocket, or am I going to have to use some other gearbox and rig the sprockets so they fit? I don't care if the gearbox is for the Leo or even Tamiya, I just want something that will work with the minimal amount of fuss getting said item to work. I have a pretty good job, but I can't just buy random gearboxes until I find one that fits. The job also prohibits spending alot of time working on things. I'm generally gone for 3 1/2 weeks out of a month(I'm a truck driver). Thank you for your help Phasor.