I ended up having to buy the nuts and bolts directly from Nissan, it cost me $77
If you are talking about the 6 bolt and 5 bolt pattern's bolts being the same diameter, I wouldn't want to be assuming they are the same. They very well could be but I have to tell you, you want a snug fit when dealing with these moving parts.
The previous owner of my car put slightly smaller diamter bolts into the halfshafts from the drive axles, and eventually there was too much play in the two components, and the bolts gave way and my driveshaft fell from the car while I was driving.\
Any other questions just ask, and sometimes it's easier to chuck some pics up too. GTS-4 is probably different to the GTS-t stuff I've been dealing with. How many bolt are you half shafts and axles, and is it just the nuts and bolts that you need?