Now I have no crushing need for an answer, just thought this was kinda puzzling.

As I have been cleaning up the original bolts and screws I noticed

that all of the M6 x 1.0 bolts have the number 4 stamped on the top.

Just trying to figure out what it signifies, strength perhaps?

I ran across this document during my travels...it will answer your question & more. Enjoy!

Datsun Torque Specifications.pdf

Now that's a cool .pdf. Thanks Jarvo!

Excellent contribution! Interesting to read the cautions regarding bolts going into aluminum or plastics, and others about compensating for friction due to rust or other issues. Finally the best comment - rely on the FSM.

Now I know, thank you.

This is great information. I've downloaded it for my records. Thank you so much!

Thats a great document explaining bolt torque specs. Added it to my collection. Thanks a lot:classic:

Ive always used an old workshop manual by Tom Monroe for bolts where I couldnt find the tension in the FSM. It has a table in the back with most of the figures. Although not as comprehensive.