The new emaxx tranny is a much improved tranny better than the revo stock and is already set for 2nd gear only.. brushless ready and keeps a nice low COG. You can run dual 2s packs for a nice 4s or even 6s config with great overall balance still.. the new tranny has 1 motor lined up dead center so it's perfect for a single XL or similar sized motor. Take a look at my thread for more detail..
http://www.rc-monster.com/forum/showthread.php?t=9470