You might try: Olander Suppply Co, Inc, Sunnyvale, CA (408) 735-1850.
If they can't help, they may be able to point you to someone who can.
> Date: Tue, 9 Apr 2002 14:55:22 -0700
> From: "Sean O'Boyle" <email@example.com>
> Subject: NAS Hardware
> Anyone know where I can purchase NAS hardware?
> Specifically I need a 5/16-24 bolt with a 1.875 grip length.
> I also need a reduced height 5/16-24 lock nut ("nylock") and a couple of
> washers to match.
> PS - for those of you who know the application I looked into pins and
> couldn't find anything that matched the NAS spec of 95,000psi shear.