You can get out the Dremel tool and grind a few fins where the fins hit the Tranny case,I have heard alot of guys say they do that.Also you can use Jato spur gears and witch are smaller than the E-MAXX spurs and allow for more gearing options,do not use T-MAXX spurs they are the wrong pitch olny use the Jato spurs they are the same pitch as the E-MAXX.
Ass soon as neu sends my 1515 1.5d/f back I can see what will happen. I had success with a hacker c50 motor, which is slightly larger than a neu finned can. I used 18/48 mod 1 gearing.