RE: 21st Century 1:18 1/2 Track
Panzerwaffe, I used the Tamiya dual motor gearbox and just connected the shaft to the stock sprockets. I have a dual motor speed control installed but I am using it in parallel and not mixed. Steering is done by the steering servo alone and it does steer pretty good. I've thought of going back and installing a y harness and mixing the speed control and using the steering servo to assist but I haven't had too bad a problem with the steering and it can wait.
Nick