Well, I'm not getting any closer to sorting this out. I've rung around a few Nissan parts dealers (in NZ) and given them the part numbers in the hope that they could get back to me with the cc ratings etc.. but so far they have been useless and not interested in helping.

The ones in the car are brown2W50-0701N-3 and the two spares I have been given are brown1M50-0530D-2 and grey1M50-1116D-2 So if anyone out there is able to search these part numbers and let me know whats what it'd be VERY much appreciated.

Cheers