MakerFarm Prusa i3 and i3v 66 oz. in. Stepper Motor Specifications

[printbus]

...it would be good to replace the motor, it's really scarily hot during printing.

Although you could do it, replacing the motor or going with a different extruder should not be a prerequisite for you to get your i3v up and running. Continue the dialogue in your print problems thread so we can help figure out what is going on in your case. Does the extruder motor get hot? Yes, as they all do with the driver setup suggested by MakerFarm. So hot that you can't keep fingers on it or hot enough to melt/soften the small gear? IMO, they shouldn't be getting that hot unless something is wrong. Make sure your power supply is set for 12V and not something else common like 13.8V. Lower the driver some. Unnecessary load on the motor will also cause it to get hotter than it should. Too low of a nozzle temp, motor and small gear pushed into large gear too tight, poor lateral alignment between small gear and large gear, dragging at the guidler bearing, large gear cranked onto hobbed bolt too far, and bolts rubbing on the large gear come to mind as some things that would put undue load on the extruder motor. I've since adopted Clough42's extruder motor shroud, but until I did that I ran long prints with a small table fan set next to the printer on extruder motor side. Fan airflow was angled upwards to not affect the bed and nozzle much, but the extruder motor would pass into the airflow when it was on the right-hand side of the prints. That kept the extruder motor noticeably cooler.