I have a 1948 GM Canada paint chip sheet where Oshawa Blue (code 834) is illustrated along with Commercial Blue (code 830). The chips on this sheet are very dark but several numbers are included. FYI your Oshawa Blue is Opex O-K Lacquer P-1236, Fleet-X Spraying Enamel X-16607. The same colour goes back to 1940. Sorry I can't be more help. I had a similar problem with my 1948 (Commercial Blue) but the firewall produced some usefull looking samples behind grommets.