Yes and no. The only suitable unit that I am aware of - assuming that you still have the final drive reduction and need an additional stage before that - is the ev-TorqueBox. It is stronger than most conversions need (because it was intended for trucks), and it is a limited-production product, so it seems wildly expensive to me for what you get... but it works. Apparently there are various ratios available, but I doubt that they are as high as 3:1 or 4:1.If I chuck out the transmission in my EV conversion project, how do I gear down the revs from the motor to the wheels? Are there off the shelf single speed "gearboxes" with a 3:1 or 4:1 ratio or thereabouts?