The box went straight in, only thing I noticed that was different was the filler plug was on the other side, but no problems.
The gear lever was a far better design, it spread the wearing surface and had some very hard nylon inserts, but alias, would not fit so I had to use my old lever with washers to fill the gaps.
To me it seems more than worn parts, the Bluebird box makes that notchy sound and the gears are all in specific locations, not generally over here and there.
The gearing feels a bit better to me, not much in the numbers. One thing I wanted was a longer 5th, but the 280ZX is the one with that!
Gearbox FS5W71B as fitted to the SI & SII Bluebird: -
1st..3.321
2nd..2.077
3rd..1.308
4th..1.000
5th..0.833
Rev..3.382
FS5C71B 260Z
1. 2.906
2. 1.902
3. 1.308
4. 1.000
5 0.864
This was cheap box, $140 off eBay which is a lot cheaper than want you would pay for a 260 box.