Hey Nathan,
I swapped the diff out of my 82 Euro Spec MkII (body same as a XX - no flares , but does have 5MGE, 3.73 LSD F series) a few months ago (for a 3.93 LSD F series). Do you have/need anything (eg another car) to compare the setup of the rear ends with?
I'm in Perth - lmk if you need any info about the diff swap.