hardware screw bolt head stamp marking
 

Does anyone know who the manufacturer of a machine screw or bolt would be if it has NAT on it?

I don't recognize that bolt head marking https://www.electronicfasteners.com/...onmarkings.pdf
Was it ink marked like for ringing up at the checkouts?

Hi Rob,
I’ve seen bolt heads with N A T before, but I have no idea what they were used on.

The charts I found don’t list it.
Seems NAT would stand for National ?

Where did you see this marking ?

Hi Chris,
They are from the original tie rod adjusting sleeve clamps from my GTO. They're a bit crusty from the years in the Midwest winters until it went off the road in 1972.

Have seen NAT on intake bolting too.

I don't know what it indicates, but here is a NOS one on Ebay

https://www.ebay.com/itm/135412591192

Whew! That's a lot of $ for a bolt, and it's not even grade 5 (three lines).