im know fords are like this, the original engine number is the same as the number in the vin code.
so maybe try posting up or PMing me you engine number, and ill put it inplace of the number in my vin, and see if it comes up with an S12 on FAST and a year.
or you may have to get in touch with nissan, but this will be a long drawn out process.
lets try the engine number first.
in case you dont know, the engine number is located on a flat bit on the exhaust side on the engine block, right at the back where the bell housing bolts on, you can see it in situe. it will start with CA18 - XXXXXXX