well......for the MTX75..........there is really only two options, and one of them i dont even know if it is possible.
there are no 3.82 gearsets available for a 8.8 rear end. there IS one for the 9" rear end.
now the other thing is that the cobra rear IRS has nearly identical moutning points to the 8.8 rear.......so that shouldnt be too bad to mount to the focus, as it was in that picture on page 4 i think
the cobra rear IRS is a 8.8
sucks for me. now the other option i was speaking of is to see if a custom gearset could be made for 3.82 for the 8.8
then i would be all set.
i would use the cobra IRS with a 3.82 and be golden.