[Ryan Foley]

First of all, good work so far. I do have a suggestion how ever. You may want to consider enlarging the outside plate (closer to the sprocket). This does 3 things:
1) you can support the motor output axles in 2 places
2) you can move the cross beams higher, above where the motors mount, to help strengthen the motor mount plate
3) makes machining easier, as you could make the same plate twice rather than making 2 different ones.

Again, good work so far, and congrats on posting your first gearbox on CD, that takes some courage to do.