Yeah. for a tt, i'd just do a full lock on the rear. I THINK u have to use "lock-tight" or something like that cuz it's gears. But, locking diffs is fully optional. I drifted just fine for like 6 or 7 months b4 locking my rear diff. And the only reason i did it is because a friend of mine was waiting on a part for his 1:1 car, had nothing to work on, and starting tinkering with my RC and i just didn't feel like undoing it. ( all it is is a screw and a pipecleaner). I unlocked it later and just re-locked it so I could use the pipecleaner as a mod for universal exhaust. it helps, but it's not needed.