The Rx8 fits just fine inside all of most common 4wd Sc's that are on the market today. It's "size" is not a issue in the class and has proven to be a winner taking wins all over the world. The combination of the Rx8 and Pro 4 motor is used by factory drivers from nearly every team such as TLR, Team Durango, MIP and AE. There are other mfg's offering much larger "units" than the Rx8 for the application

There are great choices to be had by many companies.