I know the size of the bolt, but my question is what grade bolt are the motor mount through bolts supposed to be. I see head mark bolts with the letter "C" with three radial lines (grade 5) and I see head mark bolts with the letter "A" with six radial lines (grade 8).
The car is a 1969 Z/28. No one knows what grade bolts they have for the through bolts for the motor mounts.
I believe the originals were grade 5. But probably doesn't make a whole lot of difference.
I am not sure if this is a judged item, but I will be taking my car to the Camaro Nationals and want to make sure I have the correct bolts.
They may be more concerned about the original high dollar mounts & not see the bolts...Joe
Prior CRG discussion on fasteners and hardware:
https://www.camaros.org/forum/index.php?topic=9140.0
The 1968 motor mount through bolt has fine threads. 1969 motor mount through bolt has course threads.