Cheap gearboxes (DeWalt and Globe) for Offseason project

[dbonar]

An off season project involves 20:1 gear reduction on some 775 motors (BaneBot, Vexpro, or random other). These will then be used as drive motors with the expectation that at times they might have survive outputing the stall torque (roughly 20N-m) at times with long run times at fairly high power output.

The Magnum Planetary looks good but its $90 which is more than I can justify for the project. Thus I'm left with options like modifying a DeWalt gearbox or finding Globe motor/gearboxes.

Does anyone know the pinion info for those?

Is there any place to buy a Globe motor to take the gearbox off? I'm willing to hit junkyards but I'm striking out on finding the part numbers of suitable ones to look for.

Are there other options that I'm missing to do 20:1 reduction?