Somebody asked about the ss 5800 and will it fit in the xx-4. Here's the answer. However if you have the motor leads facing top, the body will hit. I mount my motor so that the solder tabs are at like 5:00 looking at the right side of the motor. They barely hit the chassis with a 17, 18T pinion, I put some electrical tape tripled up on the floor of the chassis just for safe measure.