r230 will not bolt in into a s14 subframe ,u need to do alot of modification to make it fit,and q45 is six bolt style axle ,but look luck finding a 300zx tt axle and even know is a r200 u problem will not be the diff will be the axles braking,gtr and q45 share the same splines on the axles thats why people upgrade to them ,trust me i dont need more than a q45 axle and tt axles along with the q45 diff ,i personaly have made 900hp and have lunch the car a bunnh of time and my axles are still here i could even send u some video if some cars running low 8's and even 7's on the same set up
