[jeffschevelle]

For comparison, the 67 Camaro AIM lists 3846202 "SCREW ASM" which I know first hand is a screw with a floating washer (same as a the version of a front sheet metal screw that has a washer).

I checked on the Parts Wiki to see if 9420555 is listed anywhere, in case it would have a description of the bolt type listed. Interestingly, it is not listed in any of the Chevy parts books on the Wiki, not even the "Standard Parts" book. But it is listed in an Olds book as:

- front lower shock "bolt" for a 67-70 Olds (except Toranado), and

- shifter attaching "screw" on a 70 Olds with floor shifted TurboHydramatic.

I checked AMK and they don't have anything with 9420555 cross-referenced as the OEM part number. I don't think similar design bolts were necessarily grouped together as to their part numbers, so this is probably completely irrelevant; but they do have 9422550 which is a shorter version of the exact same style 5/16" bolt in the first picture above, and 9423545 which is a longer version of the same bolt. For whatever that may be worth ...