Understanding the letters on the bolts

[Michael Maresca]

I would like to understand the different letters on the heads of the bolts for my 67 GTX. I noticed 2 different ones that are used in the front end. One has a G over and L. The other has a N and L attached to each other. Is there anyone out there that can explain?

 

[dadsbee]

Just the manufactures markings...

 

[mr_belvedere]

Like dadsbee said, manufacturer mark.
I believe the GL is for Great Lakes Fasteners. NL National Lock Fasteners.
(Credit: David Wise, book ‘Guide to B Body Fasteners-1968-70)

 

[Photon440]

There are two pages of bolt markings in the MCC restoration guide:

 

[Michael Maresca]

There are two pages of bolt markings in the MCC restoration guide:
View attachment 1940900
View attachment 1940902

Do certain bolts go on certain pieces? On my car, the GL bolts fasten the Stone Shield, while the NL fasten most everything else up front.

 

[YY1]

Do certain bolts go on certain pieces? On my car, the GL bolts fasten the Stone Shield, while the NL fasten most everything else up front.

It's mostly the year, but also can be the plant.