Gibson Headstock  Suggested by CheopisIV 
Gtartings  Suggested by Deleted user 605223 

Unless this has since been digitised, I don't think it's a font.
This explains:
http://www.mylespaul.com/forums/luthiers-corner/196827-gibson-font-full-alphabet.html

All I could find is a font that includes the logo. I hope that's okay.

Digitized font, improved over the lettering above. Scalable and installable but requires manual tweaking of letters to situate them. Made this way for ease of using any lettering.

http://sigilpickups.com/product/gibsonstylefont/

how do i download it?

Closest font is "Gibson Headstock", in the link just above your post.
On the page, there's a purple button which says "Add to cart".
If you click on it, there's a message saying "“Gibson Style Headstock Font” has been added to your cart. View cart".
Click on the "View cart" link.
There's now a "Proceed to checkout" purple button.
Click on it and follow the instructions.