The NTC3 diff with the friction ring can't be tighten down to lock it , like a solid, no matter how tight it is, it will still slip some. If you feel the need to have a locker, use the electric TC3 diff in the front it does'nt use the friction ring. AE will tell you it won't hold up but this is just BS, we used the electric diff in the NTC3 for a long time with no failures.