Hey bud, if the diff has already been modified to suit your car any old diff shop should be able to have the axel's and drum modified to change the p.c.d.
if it hasnt been done yet start with a tarago diff, there already 4x114.3.
aussie diffs in currumbin, gold coast.
nerang differential services in nerang, gold coast.
not sure of any shops in brisbane. One thing how ever, I have found with dealing with diff mechanics is there always ass holes and no matter what you say or your knowledge on what you need done they are always rite.