[EricH]

Adam's right, output RPM of the gearboxes might not help that much.

For example, it is ridiculously easy to change it. Just change the output sprocket or the one on the other end of the chain. Your wheel spins at a different speed.

Or, the final output to the wheels might be different from what it's supposed to be. (Note to self--Next time mecanums are used, reverse the Toughbox-to-wheel chain-run sprockets.)