Which is better, ARB/KAM? well that's a lovely kettle of fish your about to open.
ARB is more popular due to being around longer, KAM has just been redesigned.
KAM requires modifing the axle and can be built as a limited slip as well.
ARB requires a hole in the diff casing and a compressor (air supply) fitting.
Both are evenly priced.
Would be worth speaking to
Devon 4x4 and
KAMDon't forget Trutrac and detroit.