When My dad and I were looking for motors, we ended up getting two 24 volt NPC motors and the gear boxes that went with them. I made an aluminum housing so the motors are on top of each other. The motors go through a reduction with the gear box and then go through another reduction with a single step chain drive. I got rid of the V-belts because my tank required to much torque to use them. My tracks compensated for the V-belts because they are the intralox conveyor belts with the smooth surface. If the tank gets stuck, the
tracks free spin on the ground. It turns great and runs fast for a heavy tank. I used a 10 tooth #35 roller chain sprocket. The chain ran to a 32 tooth sprocket from small parts catalogue.
In the pictures I removed the logic coil battery because I am working on a turret servo which is powered off of it. I have also removed the receiver and receiver battery. The black marks on the tracks are slices of 3M tape that are used for traction on steps so people don't slip and fall.
The motors and gear box came from: