None of the Skylines meet safety regulations. The reason why some R33s and R32s are legal is bc 2 companies spent the time and money to modify and crash test those cars so that they meet the standards. When they wanted to do the same with the R34s govt changed some law and they never got to be modified to meet safety specs (or something like that, its all on the link I posted before) The document of what needs to be done to bring certain year R32s and 33s can be downloaded here:
http://www.nicoclub.com/articles/NHTSA-update.pdf