The .18tz should be more powerful than the traxxas 3.3, but the 3.3 traxxas is a strong motor also. The 3.3 will be a decent bit cheaper. O.S. engines are knows for great longevity though. The O.S. is rotary carb, which is what yours is stock. The 3.3 traxxas is a slide carb, so the linkage will have to be modified for the 3.3, and you will have to probably buy some linkage parts to make it work. Same with the 2.5 traxxas. The O.S. .18tz i think would drop right in other than swapping to rear exhaust. It would be crazy fast with the .18tz if the redcat will hold together

Eric