well this is the electric ON-road forum not the electric OFF-road forum, but i am a nice guy and will answer your question anyways. if you are talking about the 1/10 sidewinder combo, then yes it should fit. basically everything 1/10 should accept a sidewinder. you will just have to gear differently. assuming you used the proper gears in the first place you should be able to just drop it into a stadium truck. the stampede has big heavy tires and you should have a smaller pinion gear to compensate for that. stadium trucks are lighter and have smaller tires so you should be able to keep the same pinion gear and if the motor and ESC stay cool then maybe even go a few teeth larger.
if you want anything more specific you will have to say exactly what you have and are using. i would recommend spending 30-60 minutes in the electric off-road forum just looking around for info and searching for stuff in these forums.