My 62 SS has many markings, I think their cool, and a mystery. I do think if you look at the RPO codes, some of them will correspond with the chalk marks. Example, mine, 412- power brakes, 148 could be
seat belts I have original belt bolts in rear seat. Large P- Powerglide, 2-Large SS's, my car was from VN Cali. My Bel Air had many also but was from back east. I did replace them on my Bel Air, they are
on the drivers side back on the firewall. Its always up to the owner, that's what makes these car's and
site so different, you can agree to disagree, and still not Impeach.....
God Bless America