Hi matey ... Welcome to the forum...
In my unqualified opinion, why would you assume that mustangs were made in RHD here in Australia?
They were a US only model with a small cottage industry to convert as needed...
Each converter used their own imagination to do the conversion...
There were some mustangs which were designated as Australian delivery over the years but I believe even these were not done inhouse at Ford here in Oz...
To top it off, the 2nd gen Mustangs are almost non existent here anyway...???