Juts because I'm bored and suffering from insomnia again I decide to do a bit of searching of old pictures.
Regarding use of Nyloc's on early Datsun vehicles. The only people it would be really important to ( IE: correct style nuts ) is collectors and Vintage restorers. The Nissan Nylocs were what are referred to as " Tall " Nyloc nuts. I've worked on many, many, Datsuns, Honda's Mazda and other Japanese cars back in the 70's. Rallied and Raced 510's, 1200's and Z's Nyloc nuts were quite common on suspension parts in those days. Not to say that there weren't " crimp " style nuts used on some big bolts as well. FWIW
It's hard to find pictures of original 240Z suspensions.. but here's a restoration of a 1968 510 with original suspension. Look carefully and you can see OEM Nyloc's nuts on lower control arm pivot bolt, sway end link bolt and TC rod to lower control arm bolts. You'll have to take my word for it I guess... or not. It's up to you.
Edit: I also found a picture of an OEM 510 in an old Datsun book ( circa 1971 ) showing the front suspension components. I'd have to scan it, but this picture also shows the OEM Nissan " Tall " Nyloc on the threaded end of the TC shaft as well as other places. Now, I honestly can't find any pictures of OEM 280Z front suspension, but by then Nissan may have superceded the nuts. But my 9/70 street 240Z that I purchased in 1975 came with Nyloc's on most of the suspension parts, including the big TC rod nut. Same with my 1971 240Z Race car, 1968 510, and 1971 Datsun 1200 . Just sayin' guys... I sold the actual OEM nuts and bolts for these cars... and although I'm now 61, my memory for OEM Parts hasn't faded that bad. All FWIW... peace.