[AdamHeard]

For high reduction arms, depending on how they are loaded, it's possible the motor never even comes near stall torque, so aluminum may work fine.

Also, if you space your plates 1.125 apart, you can make this same gearbox with ZERO custom shafts, and the use of no spacers, by utilizing the toughbox and cimple box gears. It's a trick we've been using for three seasons now.