There's a ton of guys out there that know there's a difference between grade 5 and grade 8 bolts, but have no idea what an aircraft spec bolt is, what the different letters/numbers mean, much less why they should be on your car. Here is the simplest two page summary that I have ever come across that explains the difference between the different specs (airframe bolts, close tolerance bolts, NAS 624/MS 21250: etc.):
http://www.coastfab.com/uploads/4/1/...s_general1.pdf