Well, actually predator it was mentioned in my first post that I put it into a GTS4 & thit it's an R33!
Anyway, I believe the diff center should bolt up no problem, but the the axels need to be changed because the output flanges on the GTR dif have six bolts (evenly spaced). To change to GTR axels, which are thicker & have a larger spline where it goes ito the hub, means you need to change the hubs as well!
Let me know & I can easily measure the length of the axel or spacing of the diff bolts for you.
The attached picture might help you compare it to your current setup.