Hi I am fitting new KYB inserts to my z and have found the large retaining nut which secures insert to inside of strut does not screw in all the way as it tightens so far against insert and still shows some threads is this the norm thanks
Unless originality is a concern, you should be able to replace them with any 10.9 grade calipers bolts of the right size / pitch / length.
Given that I have the S12W calipers of a Toyota Hilux on the front of mine with original Datsun bolts, I suggest you can get the Hilux bolts onto ours. I assume an LN130 1989-1993 Hilux is slightly easier to find parts for than a 50 year old Datsun.