RE: Redcat Racing Tornado Thread
The biggest easy swap would be the os 21tm. It will take a little modification though. It has a slide carb so you will need to use a L shaped arm on the throttle servo and buy a roto start for the trx3.3. It would be easier to just use the trx3.3 though and it has tons of power. Just buy the multi-shaft version. Besides that the 3.3 is around $100 less then the 21tm.