lol there is no way in hell that the universal 'rail' (which is in-fact just a sliding mechanism, no base) will fit into a skyline without some welding.
John the jjr rail will work, you may need to drill your own holes in the jjr rail to mount to seat to, that is it. But they mount the seat pretty high.
And you can't use the rail that is already on the car, as you will need to re-weld/cut/hack it up to mount it to the bride style seat.
The ///M runs one of these (to fit e36), I run one in my car as well.
http://www.nzkw.com/index.php?main_page=product_info&cPath=104_93_96_130&products_id=250
Attach the slider that comes with the seat onto that base, nice a low. easy.