This is all a bit of a blur now days,and the 3 guys that would be spot on are:1 retired(Gordon Dobie)John Roxburgh,Doug Whiteford unfortunatly long passed along with a few others,on this site only Vixen to my knowledge worked for the racing team and dearlership as a young apprentice at the time.For memory this is how it went.For homologation 100 examples where required to be sold(not registered but could be)and i remember when the Bathurst car arrived it also came with several containers full of spares,virtually complete cars in CKD,which would have counted,but as stated previously they where only required to be sold ,so this meant dealers where able to "own" these things on thier floor plan,but not actually pass them to the public but back to Nissan after a period of time,i might add,back in the 70's you would'nt want to own a new GX as raced as they where full blown racing cars with none of the nice things we wanted back then,imagine Mr &Mrs Average working thru a dogleg gearbox at every set of lights,no carpet or insulation,specially pressed lightweight panels and no radio to listen to...i could go on and talk suspension but you get the picture.Now trying to find a genuine example in Aus. i reckon will be like trying to find a needle in a haystack(huge haystack)cause i feel that maybee 20-30 complete genuine cars ever really turned a wheel and then maybee only 10% as dailys the rest as racers and rally cars only.The CAMS regulations on homologation back then where really loose and frankly cheating was bordering on out of control,and no one did it better than Nissan.
If it was me looking for a REAL GX i think i would look to Australias eastern island.
As for 5 speeds being available in Coupes in Aus.,sorry not available as an option,not when i purchased my new one anyway,but you could purchase one from spare parts for a house deposit fit it and void your new car warranty.
Good luck anyway..let us know how you get on.