The amazon search term for rear wheel 26" motor kits is : electric bicycle e-bike 26" rear wheel motor conversion kit
If front motor, substitute that term. If wheel diameter is not that size, substitute the size you have. Same search should work on e-bay.
I don't suggest trying to buy a motor wheel without a controller, they often don't match up. Also the controller is only $35, and the brake switches and throttle often don't match up between individual units. Even long term suppliers like ebikeling.com change vendors from time to time and their new parts won't fit their old controllers.
If any internally rounted wires don't match the new kit wires, run new wires externally. If the battery wiring is internal, you may have to learn to solder on an XT90 connector, crimp on an andersn connector, or crimp on 30 amp .157" diameter bullet connectors from Dorman at the auto supply. The crimp tool fot the bullet connectors is rather standard and dorman sells those too at the auto supply. Pull test crimped on connectors before using.
