Anyone know of a good resource for researching original Chevy bolt head markings? I'm interested in primarily drivetrain & engine compartment bolts.

Thanks! Mark

I have been following head markings, there was some old magazine articles and other misc papers. What are you looking for exactly?

I'd really like to verify all of them but for right now I know the intake, valve cover, water pump & thermo housing are not all original.

The info I have for '68 396/325 (L35):

Intake: grade 5 flange head with circled A marking
Valve cover: grade 1/2 hex head with large TR marking
Thermo housing (660): grade 5 hex with different KS, TR, M, P combos (which is it?)
Water pump: no info

Can you verify any of these? Thanks ... Mark

Mark, you kinda stepped out of my comfort zone quick. :) I concentrated on 69 SB bolts for obvious reasons :D But I can tell you A, M, TR bolts were used most commonly. The others are RBW, SBC, C and L5. I have not heard of P or KS. Most of the bolts were bought in batches and dumped in the bolt boxes for that assembly, so mixed markings were common, but I would stick to one marking for the whole assembly. Like all intake bolts have same mark, all pumps same, etc.

The PDF catalog here http://www.amkproducts.com/ is a very good reference. Luck!

Thanks Kevin ... I found AMK after my last post & got some answers to my questions. Downloaded the PDFs for reference.

Mark