Honestly, anything over 2s for drift is overkill. Regarding the diffs, a 1way diff is for the front only. When youre on the throttle, all 4 wheels get power. When you hit the brake, only the rears will get brake, acting like an e-brake. The front will just roll freely under braking. I use a 1way inthe front, and a locked diff in the rear, otherwise known as a spool.