mtx is the only way forward,or 6 speed st170 box,had my mtx,with quaife atb in for approx 2500mls and beleive me it aint had an easy life,i put a standard mtx in as a test subject to start with,thats as they come no mods whatsoever,i abused it for over 1000mls and try i may,i could not brake it,good goin considering i had done 9 ib5 boxes in under 10 months.