California Mustang

Recently purchased a black plate LA car that was made in Dearborn, MI> rather than San Jose? I thought all stangs up to 69 were made in San Jose that stayed in Calif. and west, I verified this with my orignal invoice from Lois Eminger and info was correct. Is that a rarety. or any others out there have the same. I really recommend spending the 30 bucks for an invoice on your dearborn,metuchen made car it just authenicates everything! Thanks