In the north american market the roller rocker motor was introduced in the 2000+ G20. In other markets I don't have specific info on when the Primera motor came with roller rockers.

It's really easy to check but you have to pop your hood. The spark plug channel is a lot deeper on the roller rocker motors than the old 'pad' style. If you haven't seen both types of motors how can you tell?

Here is a pic of the non-roller rocker motor:

And here is a pic of a roller rocker motor: