There was a long post on this subject last year. Some plants used more crayon marks than others. If there were any marks on my '68 Fremont-built C/10 stepside when I bought it in 1973, I probably went after them with rubbing compound and fresh Turtlewax. ''Damn graffitti, Grrr @#^&*%$, Out damn spot!''
Now, they're revered as some sort of provenance of originality. Fifty thousand dollar Barrett-Jackson trucks have unusually prominent firewall crayon scribbles -- no doubt a testiment as to the mint originality of the truck offered.
I don't want to name anybody specifically, as making fake firewall markings, but LMC will sell you the same kind of big crayons that the factory used.
