Gear ratio exactly the same... Only thing i know for sure (from first hand experience) is that you can't get spare parts for series 1 gearboxes. For example i wanted to change 1st-2nd synchro. Called nissan and due to a supersession i needed to replace all synchro's, selector and a long list of other things... Trade price quote came to $2600... In short the series 1 is fine as long as nothing goes wrong in it...