maybe its not the gear box, maybe theres an issue else where, the car will only drive in 3rd gear when in limp mode, ie theres a major issue somewhere, 100kmph at 4500 kinda sounds like 3rd gear
so basically....
you need your nissan super code, if you dont have that get it from nissan japan, then you'll need $500 and goto your local nissan and get a new key cut/programmed??
I hear that the problems assosiated with the gt-8 transmission failing is due to it being serviced incorrectly, ie incorrect oil being used on compliance and/or servicing. anyone know of this one??