Thanks for your interest mate. These will fit straight into the factory center gauges on a r33gtr. there is a picture actually of these gauges in a r33 skyline dash on the side of the box. In the picture, these din gauges are installed under the climate control on the r33 dash. These gauges come with everything required to fit it in, all wiring and sensors included. All you need is to provide your own water temperature sensor adaptor, and oil temp/ pressure adaptor to plug the sensors into. The water temp sensor adaptor can be the one you fit into your coolant hoses, and the oil temp/pressure can sensor can be fitted into your oil sandwich plate if you have one.
I have these adaptors for sale, but they are for sr20.
have a look in this link to see the adaptors i am talking about.
http://www.nissansilvia.com/forums/index.p...ttach_id=267395
http://www.nissansilvia.com/forums/index.p...ttach_id=267187
Let me know if you want the gauges! cheers mate